F. moluccana is a medium to fairly large-sized tree up to 40 m high with a small buttress. The bole is branchless up to 20 m and up to 100 cm or more in girth and in dense stands is generally straight and cylindrical. When grown in the open, trees form a large canopy, which is umbrella shaped. In plantations of 1000-2000 trees per ha the crowns become narrow. The bark is light grey with warts, inner bark smooth and pink though young parts may be densely reddish brown tomentose or puberulent. Leaves alternate, bipinnately compound and 20-40 cm long with 4-(10-12)-15 pairs of pinnae, each pinnae 5-10 cm long containing 8-(15-20)-25 falcate leaflets 10-20 mm long and 3-6 mm wide, pubescent, dull green above, paler below, obliquely elliptic, falcate, midrib strongly excentric near one of the margins. Leaves each have a large nectary below the lowermost pair of pinnae and smaller ones between or below most pairs of pinnae. Flowers are large, branched, bell-shaped, in paniculate axillary racemes ca 20 cm in diameter, often with 2 serial branches from 1 bract scar;calyx 1-1.5 mm long, silky pubescent, the teeth 0.5 mm long. The flowers are bisexual, regular and 5-merous. The corolla is creamy-white to greenish-white and sericeous 3-4.5 mm long (excl. stamens);stamens 10-17 mm long, numerous and extend beyond the corolla. Pods are narrow and flat, densely pubescent or glabrous, green turning brown and splitting on maturity, 10-13 cm long and 1.5-2.5 cm wide, winged along ventral suture with many (ca. 20) transversely arranged, ellipsoid, flat dark brown seeds, 5-7 mm long, 2.5-3.5 mm wide.
Erect, woody perennial herb or small shrub, up to 3 m tall, but usually around 1.5 m tall. Stems and leaves are covered with star-shaped (stellate) hairs, often many branched at the base. Leaves are simple, alternate, with the upper surface rough and the lower surface grayish, broadly ovate, often with 3-5 shallow, angular lobes at apex, up to 10 cm long, margins finely toothed, bases heart shaped, petioles up to 5 cm long, stipules tiny. Flowers are small, showy, hibiscus-like, solitary on short stalks in leaf axils, subtended by 5 basally united (involucral) bracts up to 0.7 cm, calyx 5-lobed, hairy, 5 petals, rose or pink, darker at the base, rounded, up to 1.5 cm long, stamens fused into an obvious pink column beneath a 5-lobed style. Fruits are small, barbed, spiny capsules, up to 1 cm across, with 5 prominent segments each containing 1 dark brown seed (Francis, 2000, Langeland et al., 2008, Queensland Department of Primary Industries and Fisheries, 2011).
U. lobata is a severe weed in pastures, sugarcane fields, coffee plantations, rice plantations, and perennial crop plantations in many countries around the world (Henty and Pritchard, 1973;Fournet and Hammerton, 1991;Martin and Pol, 2009;Randall, 2012). It is considered a weed in forest plantations in Bangladesh (Akter and Zuberi, 2009) and India (Chandra-Sekar, 2012). U. lobata is also classified as a noxious environmental weed because it has the potential to alter native plant communities by displacing and out-competing native species, changing community structures, and altering ecological functions (Austin, 1999;Florida Exotic Pest Plant Council, 2011;USDA-NRCS;2012).
C. imbricatus is a coarse, rhizomatous perennial, 70-150 cm tall;rhizomes short, 1-3 cm long, 5-10 mm thick, hardened;roots coarse. Culms erect, trigonous, often subtriquetrous distally, firm, coarsely ribbed, smooth, 3.5 -10 mm wide, sheathing bases 1-3 cm wide. Leaves 3-7;sheaths eligulate, spongy-thickened and purple-black proximately, fading to brown streaked with black distally;ligule absent;blades linear, folded to V shaped proximally, plicate distally, 35-90 cm ? 4-15 (-18) mm, with numerous cross veinlets, scabrous on the margins, abaxial mid-vein, and adaxial lateral veins, long-attenuate to triquetrous apex. Inflorescence a compound umbel-like corymb with ascending rays, 12-30 ?14-30 (-40) cm;involucral bracts 5-10, leaf-like, spreading, ascending to horizontal, the lowermost to 90 cm long;rays 6-12, to 25 cm long;spikes linear-cylindric, 1-6 (-8) cm ? 3-10 (-15) mm, in subradiate groups of (1-) 3-20 at ray tips, with (20-) 30-130 (-160) densely disposed spikelet, compressed, often slightly twisted, 3-6 ? 1-1.4 mm, acute to obtuse at apex, obtuse at base, with 8-22 florets. Stamens 3, the anthers 0.2 - 0.5 mm long, apiculate;styles 3-branched. Achene trigonous, dorsi-ventrally compressed, with the adaxial face plane and the abaxial faces broadly rounded, ellipsoid to ellipsoid-obovoid, 0.5-0.6 ?0.3-0.4 mm, very finely puncticulate to essentially smooth and glossy at maturity, dull whitish to stramineous (Acevedo-Rodr’guez and Strong, 2005).
C. imbricatus is a common weed in rice plantations and banana fields in tropical and temperate Asia (Mangoensoekardjo and Pancho, 1975;Soerjani et al., 1987;Noda et al., 1994;Li, 1998;Koo et al., 2000).
B. pilosa seedlings have lanceolate (strap-shaped) cotyledons, 25 mm long, and purple-tinged hypocotyls. The first true leaf is similar to later leaves. Finot et al. (1996) describe the morphology of dry seed, unfolded cotyledons, first true leaf or leaf pair unfolded and two to five true leaves unfolded. Original drawings and photographs accompany each description.
The plant is an erect annual herb, 20–150 cm tall (in tall plants sometimes the branches straggling), very variable, reproducing by seeds. Main root pivotant. Stems square, glabrous or minutely hairy, green or with brown strips. Dark green, opposite leaves on stems and branches, 4–20 cm long, up to 6 cm wide, the lower leaves simple, ovate and serrate, the upper leaves trifoliolate or imparipinnate with 2–3 pairs of pinnae and a single terminal leaflet. Petioles are 2–5 cm long.
The inflorescence is an isolated or grouped pedunculated capitula, emerging from the leaf axil. Heads borne singly at the ends of long, slender, nearly leafless branches;narrow, discoid, the disk 4-6 mm wide at anthesis;ray florets, absent or 4–7 per head, white or pale-yellow, 2–8 mm long, disk florets, 35–75 per head, yellow.
Achenes (commonly referred to as 'seeds') linear, black or dark brown, 1–1.5 cm long, flat, 4-angled, sparsely hairy. Pappus with 2–3(–5) yellowish barbed awns, 1–2 mm long. The achenes are the dispersal units;dispersion is aided by the awns as they readily attach to animal skin, machinery and clothing.
B. pilosa is troublesome in both field and plantation crops and is reported to be a weed of 31 crops in more than 40 countries (Holm et al., 1977).
It is regarded as a principal weed of sugarcane, maize, coffee, tea, cotton, potatoes, vegetables, bananas, beans and citrus in various Latin American and African countries (Holm et al., 1977) and a serious weed in many other situations. In upland rice in South and South-East Asia, it is common in Thailand and present in Indonesia, Laos, Myanmar, Philippines and Vietnam (Galinato et al., 1999).
C. spectabilis is an erect herb 0.6-1.5 m tall. Branches terete, glabrous. Stipules ovate-triangular, approximately 1 cm. Leaves simple;petiole 2-8 mm;leaf blade oblanceolate to narrowly elliptic, 7-15 × 2-5 cm, thin, abaxially appressed silky pubescent, adaxially glabrous, base broadly cuneate, apex obtuse and mucronate. Racemes terminal, 20-30-flowered;bracts ovate-triangular, 7-10 mm. Pedicel 1-1.5 cm;bracteoles inserted at or apical to middle of pedicel, linear, approximately 1 mm. Calyx 2-lipped, 1.2-1.5 cm, glabrous;lobes broadly lanceolate-triangular, longer than tube. Corolla pale yellow;standard veined purplish red, suborbicular to oblong, 1-2 cm, base with 2 appendages, apex obtuse to retuse;wings obovate, approximately 2 cm;keel rounded about middle, with a fairly short and slightly incurved twisted beak beyond calyx. Legume broadly oblong, 2.5-3 × 1.5-2 cm, 20-30-seeded, shortly stipitate, glabrous. Seeds smooth, dark brown, 4.5 mm long (Flora of China Editorial Committee, 2015).
C. spectabilis is native to tropical Asia and has been widely introduced in many tropical countries around the world. It has escaped from cultivation and can now be found naturalized principally in open and disturbed sites. This species is a serious weed in agricultural land and natural habitats (Randall, 2012). The potential invasiveness of C. spectabilis is very high mainly because this species spreads predominantly as a contaminant in agricultural equipment, crop seeds, forages and hay (Maddox et al., 2011). In the United States, it is listed as a noxious weed in many Mid-South states (e.g., Arkansas), and it has spread rapidly throughout the Southeastern states where it is now considered an invasive species (Maddox et al., 2011;USDA-NRCS, 2015). C. spectabilis is also listed as invasive in Cuba, Australia, New Caledonia and many other islands in the Pacific Ocean (Oviedo Prieto et al., 2012;PIER, 2015;Weeds of Australia, 2015).
C. spectabilis is a common weed in maize and soyabean plantations in the United States. It is also a weed in active and abandoned pastures (Maddox et al., 2011).
Annual or perennial tufted, erect sedge with fibrous root system;culms slender, 40-60 cm tall, four- or five-angled and often somewhat flattened;leaves 1.5-2.5 mm wide, up to 40 cm long, basal leaves half as long as culm, linear, threadlike and stiff, two-ranked, with sheaths;leaf bract shorter than inflorescence;inflorescence a rather lax and diffuse compound umbel, 6-10 cm long, spikelets globose or ovate, 2.5-4 mm long, 1.5-2 mm wide, round or acute at apex, reddish brown, the lower scales fall early;stigmas three-branched, rarely in a few flowers two-branched;anthers yellow;glumes ovate, brown, about 1 mm long, spirally arranged, membraneous, obtuse or acute, the green midvein or keel broad.
F. littoralis is a tufted leafy annual or short-lived herb (sedge) included in the Global Compendium of Weeds where it is listed as an agricultural and environmental weed (Randall, 2012). It has escaped from cultivation and become established along waterways and wetlands (Flora of China Editorial Committee, 2014). The species is of particular concern in rice plantations around the world (Holm et al., 1977). It shows allelopathic activity and once established it can change features of ecosystem functions including hydrological cycles, biophysical dynamics, nutrient cycles, and community composition (Holm et al., 1977;Holou et al., 2013).
F. littoralis is one of the most important weeds affecting rice plantations in practically every location in the tropical and subtropical regions of the world where this crop is cultivated (Holm et al., 1977). It is also found in bananas and maize in Taiwan, abaca [ Musa textilis ] in the Philippines, sugarcane and maize in Indonesia, and taro [ Colocasia esculenta ] in Hawaii. It is reported to be one of the prevalent weeds in sorghum in Malaysia.
P. hysterophorus is an erect, much-branched with vigorous growth habit, aromatic, annual (or a short-lived perennial), herbaceous plant with a deep taproot. The species reproduces by seed. In its neotropical range it grows to 30-90 cm in height (Lorenzi, 1982, Kissmann and Groth, 1992), but up to 1.5 m, or even 2.5 m, in exotic situations (Haseler, 1976, Navie et al., 1996). Shortly after germination the young plant forms a basal rosette of pale green, pubescent, strongly dissected, deeply lobed leaves, 8-20 cm in length and 4-8 cm in width. The rosette stage may persist for considerable periods during unfavourable conditions (such as water or cold stress). As the stem elongates, smaller, narrower and less dissected leaves are produced alternately on the pubescent, rigid, angular, longitudinally-grooved stem, which becomes woody with age. Both leaves and stems are covered with short, soft trichomes, of which four types have been recognized and are considered to be of taxonomic importance within the genus (Kohli and Rani, 1994).;Flower heads are both terminal and axillary, pedunculate and slightly hairy, being composed of many florets formed into small white capitula, 3-5 mm in diameter. Each head consists of five fertile ray florets (sometimes six, seven or eight) and about 40 male disc florets. The first capitulum forms in the terminal leaf axil, with subsequent capitula occurring progressively down the stem on lateral branches arising from the axils of the lower leaves. Thousands of inflorescences, forming in branched clusters, may be produced at the apex of the plant during the season. Seeds (achenes) are black, flattened, about 2 mm long, each with two thin, straw-coloured, spathulate appendages (sterile florets) at the apex which act as air sacs and aid dispersal.
P. hysterophorus is known to reduce the yield of various crops and to compete with pasture species in various countries. However, the yield loss and specific effects on the crops have not been quantified in all countries (Rubaba et al., 2017).;In Australia, the main impact of P. hysterophorus has been in the pastoral region of Queensland, where it replaces forage plants, thereby reducing the carrying capacity for grazing animals (Haseler, 1976, Chippendale and Panetta, 1994). Serious encroachment and replacement of pasture grasses has also been reported in India (Jayachandra, 1971) and in Ethiopia (Tamado, 2001, Taye, 2002). The weed is also able to invade natural ecosystems, and has caused total habitat changes in native Australian grasslands and open woodlands (McFadyen, 1992).;In India, the yield losses are reported as up to 40% in several crops and a 90% reduction of forage production (Gnanavel, 2013). P. hysterophorus is now being reported from India as a serious problem in cotton, groundnuts, potatoes and sorghum, as well as in more traditional crops such as okra (Abelmoschus esculentus), brinjal (Solanum melongena), chickpea and sesame (Kohli and Rani, 1994), and is also proving to be problematic in a range of orchard crops, including vineyards, olives, cashew, coconut, guava, mango and papaya (Tripathi et al., 1991, Mahadevappa, 1997, Gnanavel, 2013).;Similar infestations of sugarcane and sunflower plantations have recently been noted in Australia (Parsons and Cuthbertson, 1992, Navie et al., 1996), whilst in Brazil and Kenya, the principal crop affected is coffee (Njoroge, 1989, Kissmann and Groth, 1992). In Ethiopia, parthenium weed was observed to grow in maize, sorghum, cotton, finger millet (Eleusine coracana), haricot bean (Phaseolus vulgaris), tef (Eragrostis tef), vegetables (potato, tomato, onion, carrot) and fruit orchards (citrus, mango, papaya and banana) (Taye, 2002). In Pakistan, the weed has been reported from number of crops, including wheat, rice, sugarcane, sorghum, maize, squash, gourd and water melon (Shabbir 2006, Shabbir et al. 2011, Anwar et al. 2012).;In Mexico, the species is reported as a weed in cotton, rice, sugarcane, Citrus spp, beans, safflower, sunflower, lentils, corn, mango, okra, bananas, tomato, grapes, alfalfa, chili peppers, luffa, marigolds and other vegetables and fruit orchards. It is also a weed in nurseries. In Argentina is reported as a weed of tobacco fields (CONABIO, 2018).;Gnanavel (2013) also reports the following detrimental effects of P. hysterophorus on crops: it inhibits nitrogen fixing bacteria in legumes, the vast quantity of pollen it produces (ca. 624 million/plants) inhibits fruit setting, it is an alternative host for viruses that cause diseases in crop plants, and it is an alternative host for mealy bugs.
U. platyphylla is an annual grass. Culms 25-100 cm, decumbent, rooting at the lower nodes;nodes glabrous. Sheaths glabrous or sparsely pilose;ligules 0.5-1 mm;blades 2.5-17.5 cm long, 3-13 mm wide, glabrous or sparsely pilose, bases subcordate, not clasping the stems, margins ciliate basally, with papillose-based hairs. Panicles 6-16 cm long, 2-2.5 cm wide, with 2-8 spike-like primary branches in 2 ranks;primary branches 3-8 cm, axils pubescent, axes 1.3-2.5 mm wide, flat, usually glabrous, occasionally pilose dorsally;secondary branches rarely present;pedicels shorter than the spikelets, scabrous and sparsely pilose. Spikelets 3.8-5 mm long, 2-2.5 mm wide, ovoid, bi-convex;solitary, appressed to the branches, in 2 rows. Glumes scarcely separated;lower glumes 1.2-1.8 mm, to 1/3 as long as the spikelets, obtuse, glabrous, 5(-7)-veined, not clasping the base of the spikelets;upper glumes 3.2-4.7 mm, glabrous, 7(-9)-veined;lower florets sterile;lower lemmas 3.2-4.7 mm, glabrous, 5-veined;lower paleas present;upper lemmas 2.8-3.4 mm long, 1.8-2.3 mm wide, apices incurved, broadly acute to rounded, mucronulate;anthers about 1 mm. Caryopses 1.5-2.2 mm (Wipff and Thompson, 2003).
U. platyphylla is a weedy grass species commonly found in disturbed, open and sandy sites such as crop fields, ditches and roadsides. It is considered a troublesome weed because of its tolerance to some herbicides principally in maize plantations (Chamblee et al., 1982;Gallaher et al.,1999). U. platyphylla is highly adaptable and it is able to germinate and grow throughout a wide range of soil and environmental conditions (Burke et al., 2003). Additionally, its seeds may remain on the crop residue until pre-emergence herbicides are no longer effective in controlling the germinating seeds, at which time the seeds fall to the soil surface and germinate (Alford et al., 2005).
U. platyphylla grows as a weed in maize, groundnuts, rice, soyabean and citrus plantations where it has been documented to reduce yield (Futch and Hall, 2004;Alford et al., 2005;Sesto et al., 2011).
M. umbellata is a vigorous perennial vine with climbing or trailing stems up to 3 m or more in length, glabrous or softly hairy. Young stems have a milky sap;older stems may be woody. Leaves are alternate, long-petiolate, narrowly to broadly ovate with cordate base, occasionally lobed, about 10 cm long (but sometimes up to 15 cm long). Flowers occur in axillary clusters of a few to many flowers, on peduncle 1-5 cm long. Calyx 5-8 mm long, rounded;corolla 2-4 cm long, always bright yellow in subsp. umbellata, but van Ooststroom and Hoogland (1953) note that those of subsp. orientalis vary from yellow/orange in western Malaysia to white in Indonesia. Capsule ovoid to conical 10-15 mm long, splitting into four. Seeds 5 mm long, brown, densely hairy.
M. umbellata is a climbing weed widely distributed in tropical regions throughout the world. It is one of the commonest and most widespread species of Merremia. Due to its attractive yellow flowers, it has been introduced as an ornamental in several countries where has become naturalized. It is typically found in disturbed areas and as a weed in agricultural crops and plantations, but little is known about its environmental impact. The PIER website (PIER, 2016) lists it as invasive in Hawaii, Fiji, Micronesia, French Polynesia, New Caledonia and the Galápagos Islands, although regional floras and reports (see references in the distribution table) do not explicitly indicate so. It is also considered invasive in Cuba (Oviedo Prieto et al., 2012) and American Samoa (Speith and Harrison, 2012).
M. umbellata is noted to occur in forest plantations, perennial crops, pastures, root crops and vegetables (García et al., 1975). It seems to be a common weed in rice (Moody, 1989;Fuentes et al., 2006) and in mahogany plantations from Southeast Asia (Nazif, 1992;Krisnawati et al., 2011). In Mexico, it has been reported as a weed in sugarcane, maize, sponge gourd (Luffa aegyptiaca), tomato, mango and okra (Abelmoschus esculentus) (Villaseñor Ríos and Espinosa García, 1998).
M. nudiflora is an annual or perennial herb, 8-115 cm tall, with a basal leaf rosette, disappearing or absent in older plants, with one to several creeping leafy branches, being either erect, semi-erect, ascendant, or at the base. Leaves are alternately arranged, sessile, larger ones linear-lanceolate, smaller ones oblong-ovate, glabrous, or with sparsely-arranged trichomes or hairs, 1.7-28 or 1.7-45 cm x 5-25 mm, with a broad leaf base, acute apex, short leaf sheath, and villous. Roots are normal, not swollen. Inflorescences terminally- or axillary-arranged, either unbranched or with 2-3 branches, no large cucullate bracts;bracts 25-35 mm oblong-cucullate, rather thin, membranous, caducous, located at the base of 25-40 mm long, glabrous pedicels, sepals 3, green, oblong, obtuse, glabrous, 3.5-5.0 mm long, petals 3, oblong to ovate-oblong, obtuse, purplish to magenta in colour, 4.5-5.5 mm long. Stamens free, 2 fertile with densely long-hairy filaments and bluish-coloured anthers;staminoids 4, with long-bearded filaments, the 3 opposite the petals with thickened, 3-lobed, light yellow coloured top, the fourth much reduced in size. The ovary is glabrous. Fruits condensed, ellipsoid-globose, shortly acuminate, glabrous, 4-6 mm in diameter, 3-loculate, each cell with 1-2 seeds, rarely with more than 6 seeds per fruit. Seeds smooth to coarse reticulate, ribbed.
M. nudiflora is classified as one of the world's worst weeds by Holm et al. (1977), infesting no less than 16 crops in 23 countries. It is a major weed species in rice and other crops (Moody, 1989), and is a moderately invasive weed species both in agricultural crops and non-agricultural areas in South and South-east Asia (Waterhouse, 1993). Its special ability to root easily at the nodes, propagating clonally through cut stems and dispersal during tillage and land preparation make this weed difficult to control. This trait coupled with its ability to adapt and survive a wide ecological window of soil types, pH, moisture availability and soil drainage makes M. nudiflora a weed to watch for potential spread into new areas in near future, and a species under the 'alert list' by the Invasive Species Specialist Group. Oliveira Pellegrini et al. (2016) recognize M. nudiflora as one of two Murdannia species invasive in the Neotropics.
M. nudiflora is a principal weed of peanuts, lowland and upland rice, tea, and maize in Indonesia, Philippines and Sri Lanka (Soerdarsan et al., 1974;Baki and Md Khir, 1983;Soerjani et al., 1987;Pancho and Obien, 1995). It is a weed of rice in the eastern plains of Colombia (Bastidas-Lopez, 1996;Plaza and Forero, 1998), bananas, citrus, sugarcane, vegetables, rice, maize and coffee in Mexico (Holm et al., 1977), pineapples in Hawaii, Indonesia, South Africa, Malaysia and the Philippines (Holm et al., 1977;Pancho and Obien, 1995;Baki et al., 1997), and taro in Fiji and Hawaii (Holm et al., 1977). Galinato et al. (1999) reported widespread occurrence of the weed in teak, tea, oil palm, chincona, cotton and coffee plantations, and in arable lands. In the United States, it has historically been a problematic weed in turfgrass systems, but it has become increasingly more common in North Carolina in cotton (Gossypium hirsutum) and soyabean (Glycine max) plantations (Wilson et al., 2006).
The following description is taken from Flora of China Editorial Committee (2015):
C. viscosa is an annual herb, up to 160 cm tall. Stems simple or branched, ± glandular hirsute, viscous. Petiole 1.5–4.5(–8) cm, glandular hirsute;leaflets 3 or 5;leaflet blades ovate to oblanceolate-elliptic, (0.6–)2–6 × 0.5–3.5 cm, both surfaces glandular hirsute, margin entire to glandular ciliate, apex acute to obtuse. Inflorescences 5–10 cm but 10–15 cm in fruit;bracts 1–2.5 cm, palmately compound, 3-foliolate, often deciduous, glandular hirsute. Pedicel 0.6–3 cm, glandular hirsute. Inflorescences 3–6-flowered. Sepals green, equal, distinct, 5–10 × 0.8–1.2 mm, lanceolate, persistent, glandular hirsute, base cuneate, margin entire. Petals bright yellow, basally sometimes purple, arranged in an adaxial semicircle before anthesis but radially arranged at anthesis, 7–14 × 3–4 mm, oblong to ovate, clawed. Stamens (dimorphic, 4–10 adaxial ones much shorter with a swelling below anthers) green, 5–9 mm;anthers green, 1.4–3 mm. Pistil 6–10 mm, densely glandular;style 1–1.2 mm;stigma capitate. Fruit capsule 3–10 cm × 2–4 mm, strongly ridged longitudinally, dehiscing only partway from apex to base, glandular pubescent or essentially glabrous. Seeds 25–40 (up to 100) per capsule, light brown, 1.2–1.8 × 1–1.2 mm, compressed spherical, transversely finely ridged.
C. viscosa is a fast-growing herb of humid and warm habitats. It is commonly found growing as a weed in disturbed sites, gardens, rice paddies, pastures, orchards, abandoned lands, and along roadsides (Flora of China Editorial Committee, 2015;PROTA, 2015). This species is included in the Global Compendium of Weeds where it is listed as an environmental and agricultural weed with moderate economic impacts principally in rice paddies and sugarcane plantations (Randall, 2012). It produces large numbers of sticky seeds which can be dispersed by wind, water, and as a contaminant in farm machinery, farm produce, soil, or adhered to clothes and animal fur (Smith, 1981;PROTA, 2015). Currently, C. viscosa is listed as invasive in India, Singapore, Dominican Republic, Puerto Rico, the Virgin Islands, Galapagos Islands, and on several islands in the Pacific Ocean such Fiji, French Polynesia, Guam, and Papua New Guinea among others (Waterhouse, 1993;Kairo et al., 2003;Chandra, 2012;PIER, 2015;Rojas-Sandoval and Acevedo-Rodriguez, 2015).
C. viscosa is a weed in ruderal areas, woodland, grassland, rice paddies, and sugarcane plantations (Holm et al., 1979;Flora of China Editorial Committee, 2015;PROTA, 2015).
C. crepidioides is an erect, sparingly branched aromatic annual herb, 40-100 cm tall. Stem rather stout, soft, ribbed, apically with short, thick hairs, lower down glabrescent;branches densely pubescent. Leaves helically arranged, elliptic, oblong or obovate-elliptic, acute or acuminate, pinnately lobed or pinnatifid, irregularly serrate, very thinly pubescent or glabrous, 8-18 x 2-5.5 cm;base tapered and often long-decurrent into the petiole;uppermost leaves smaller, sessile. Heads in terminal, rather small corymbs, homogamous, many-flowered, cylindrical, 13-16 x 5-6 mm, nodding during anthesis, afterwards erect;bracts linear, 0.5-10 cm long, peduncles densely pubescent;outer involucral bracts free, linear, 1-4 mm long, unequal, inner ones subequal, 1-2 seriate, green with dark-brown, acute, papillose tops, lanceolate, 8-12 mm long, thinly hairy, erect during anthesis, pellucid-marginate, cohering into a cylindrical tube, ultimately spreading, reflexed;hypanthium flat, epaleate, alveolate, alveoles with membranous rim. Flowers equal, bisexual;corolla yellow throughout, 9-11 mm long, tubular;tube long, very slender, funnel-shaped, circa 1 mm long, 5-fid limb. Anthers with entire or shallowly incised base, purple, apex acute. Style bifid, arms long, thin, their truncate, more or less penicilliate top tipped by a subulate appendix. Achenes cylindric-linear, ribbed, dark-brown with paler base and apex, thinly pubescent, 2 mm long;pappus hairs numerous, thin, silky, minutely toothed, white, caducous, 9-10 mm long (Kostermans et al., 1987).
C. crepidiodes is an invasive herb included in the Global Compendium of Weeds and classified as one of the most aggressive weeds occurring in tropical and subtropical regions (Randall, 2012). It is a pioneer species with the capability to produce large amounts of hairy wind-dispersed seeds. However, Chen et al. (2009) suggest that seed dispersal ability is limited. Chen et al. (2009) report that the species has only a moderate invasive capacity and that its wide distribution in China possibly correlates with its cultivation.
C. crepidioides may be found infesting young tea plantations (Sastroutomo and Pandegirot, 1988), in rice, taro, coffee, citrus, sweet potatoes, vegetable crops, orchards and pastures.
The following description comes from Burger and Huft (1995)
C. argenteus is an herbaceous weed of open sunny sites, pastures, and agricultural lands. It is also a common weed in rice plantations (González, 2000). Because this species grows in seasonally waterlogged areas, its seeds are often dispersed as a contaminant in dried and wet mud (Standley and Steyermark, 1946). Currently, it is listed as invasive only in Cuba, but it is a common weed in dry and wet fields in areas within and outside its native distribution range (Oviedo Prieto et al., 2012;USDA-NRCS, 2015).
C. argenteus is a weed of pastures and rice and sugarcane plantations (Standley and Steyermark, 1946;González, 2000;Torres et al., 2010).
E. fosbergii is an annual, erect or ascending herb, branched, 20 to 50 cm (up to 100 cm) tall. Stems glabrous to sparsely pilose or sometimes prominently villous-pilose near the axils of the middle cauline leaves. Leaves alternate, broadly ovate to oblanceolate, often tapering to a prominently winged petiole and therefore appearing pandurate, the base sessile to auriculate, the margin weakly serrate to dentate or sometimes lobed, the teeth callose-tipped, overall 5-10 cm long, 2-5 cm wide, about 2 times longer than wide, the uppermost leaves reduced to linear serrate clasping bracts. Inflorescence of one to several headed, loose, corymbiform cymes arising terminally or laterally in the axils of the upper cauline leaves. Heads turbinate or sometimes weakly urceolate or becoming weakly campanulate in age, robust, 2-3 times longer than wide, the florets prominently exserted approximately 2 mm beyond the involucre;involucral bracts 8-13, linear, (7-) 9-12 mm long;receptacle flat to convex, the carpopodia forming prominent tubercles after achenes have been shed;florets 15-30, varying greatly in size with the robustness of the plant, the corollas pink to light purple or red but not orange. Achene reddish brown to light tan, columnar, approximately 5 mm long with a row of strigose-hirsute pubescence on each of the 5 prominent ribs;pappus of abundant, white, capillary hairs (Flora of Taiwan Editorial Committee, 2014;Missouri Botanical Garden, 2014).
E. fosbergii is a cosmopolitan annual herb included in the Global Compendium of Weeds (Randall, 2012). It is fast-growing, with the capacity to grow as a weed and colonize disturbed areas, waste ground, gardens, abandoned farmland, coastal forests, forest edges, pastures, roadsides, rocky areas, and riverbanks (Wagner et al., 1999;Vibrans, 2011;Pruski 2014). It produces large amounts of wind-dispersed seeds (5000 seeds per plant;Mejía et al., 1994) which is a feature facilitating the likelihood of spreading and colonizing new habitats. Currently, E. fosbergii is listed as invasive in Mexico, Central America, West Indies, and on several islands in the Pacific Ocean (see Distribution Table for details).
E. fosbergii has been listed as a weed in rice plantations in Colombia and coffee plantations in Costa Rica. It is also listed as a weed in cassava and sugarcane plantations in Central and South America (Echegoyen-Ramos et al., 1996, Murillo et al., 2006;Vibrans, 2011).
H. brevipes is an erect annual plant up to 1 m high with a square stem typical of the family, often densely hairy but sometimes less so. Leaves are also normally coarsely hairy on both surfaces, opposite, narrowly ovate or lanceolate, 4-7 cm long, up to 2 cm wide, cuneate at the base, the margins irregularly serrate. Apex acute to acuminate. The inflorescence is a dense raceme, almost globose, up to 14 mm diameter, on a peduncle about 1 cm long in the axils of most upper leaves. Corolla white or purplish-white, irregularly five-lobed about 5 mm long. The calyx, 4 mm long, also has 5 narrow, finely barbed lobes. Bracts lanceolate, 8-12 spreading or reflexed, 4-6 mm long, almost concealed by the flowers. Seeds ovoid, up to 1 mm long, dark brown to black, obscurely striate, with a conspicuous scar.
H. brevipes is an annual plant of cultivated land and wastelands, including forest edges, wet ground and rice crops, and is favoured by continuous wet conditions, without a prolonged dry season. It is native to Mexico, the Caribbean and much of South America and has been widely introduced across South East Asia, where it has naturalized. H. brevipes may be accidentally introduced into a new area as a contaminant of seed, in particular with rice. It has been listed as a ‘principal’ weed of Malaysia and a common weed of Borneo, Philippines and Taiwan (Holm et al., 1979). In addition, PIER (2017) report that H. brevipes is invasive in Singapore, Thailand and Vietnam. Lorenzi (1982) describes it as a damaging weed of humid conditions along the coast, where it can develop into large infestations. H. brevipes is typically a weed of agricultural land, causing yield losses and a negative economic impact.
H. brevipes is primarily a weed of rice, especially in South East Asia, including Malaysia (Yong and Goh, 1977). In Indonesia it is noted to be a weed in rain-fed and upland rice fields, grasslands, rubber, cacao, young oil palm and sugar cane plantations and orchards (Knowledge Management Center on Topical Biology, 2017). It is also listed among weeds in mung bean in Indonesia (Bangun et al., 1986) and in Phaseolus beans in Brazil (Laca-Buendia et al., 1989).
L. japonicum is a rhizomatous vine, climbing to 30 m. Rhizomes creeping, with black to reddish-brown hairs. Stipes spaced to 1 cm apart on rhizome. Rachis grooved, pubescent to glabrous, 3-30 m. Pinnae with short stalks, 3-5 cm. Pinnae deltoid shaped, 2-3-pinnate, to ca. 12 cm long, 12 cm wide, usually with a long central lobe, margins lobulate. Costae with scattered hairs, veins and pinnae surfaces typically glabrous, rarely with short hairs. Fertile segments with 3-5 separate lobes, subpalmate, sporangia born on sorophores, each with 4-8 sporangia pairs. Spore diameters 64-80 µm, averaging 76 µm.
When mature, L. japonicum is easily detected on the ground due to its unique morphology and high-climbing habitat. However, because the species can disperse easily into remote areas via windborne spores new populations are easily overlooked because of difficulty of access.
L. japonicum is a high-climbing vine that has become established outside of its native range of Asia. L. japonicum is widely cultivated around the world. In the 1900s it became established in the south east USA and has since spread to at least nine states. L. japonicum occupies most of the southeastern coastal plain and parts of the Piedmont. Outside of its native range, L. japonicum has become an invasive species in a variety of habitats;floodplain forests, marshes and other wetlands, pine flatwoods, timber plantations and disturbed sites. It is a threat to natural areas where it outcompetes native species, alters fire behaviour and also poses an economic threat to the timber and pine straw industries. The distribution of the species continues to expand and could eventually occupy 39% of the USA;it has not yet reached the limit of distribution and abundance (USDA, 2009). Populations of L. japonicum have also become established on two Hawaiian Islands, Puerto Rico, Singapore and South Africa. Here, the species has not spread as aggressively as in the USA, but is of major concern.
In the Philippines L. japonicum has been listed as a weed of upland rice (Moody, 1989;Galinato et al., 1999).
In southeastern USA it is an invader of pine plantations (Pinus spp.) (Beasley and Pijut, 2010).
Herbaceous, twining or creeping vine, attaining 3 m or more in length. Stems cylindrical, usually reddish, with long, erect, yellowish, non-glandular hairs. Leaves alternate, 5-palmately compound;leaflets 4-14 x 2-6 cm, oblanceolate or elliptical, the apex and base acuminate, the margins entire and ciliate, hispidulous to glabrate on both surfaces. Flowers in dichasial cymes;peduncles shorter than the petioles, hairy;bracts deciduous;sepals subequal or unequal, 1.5-2 cm long, with long, yellowish hairs;corolla funnel-shaped, white, 2.5-3 cm x 4-4.5 cm;five stamens, white;stigma bilobed, white. Fruit capsular, 4-valvate, subglobose, 1-1.5 cm in diameter, light brown, glabrous, surrounded by the persistent sepals. Four seeds per fruit, obtusely triangular, 5-6 mm long, brown, glabrous (Acevedo-Rodríguez, 2005;Austin et al., 2012).
M. aegyptia can be easily recognized in the field by the 5-digitate leaves with entire leaflets, and the long, erect hairs covering the stems and calyx.
Merremia aegyptia is an annual climbing herb that acts as a pioneer species in disturbed sites in tropical regions. It is considered a weed in most countries where it occurs and it has been included in the Global Compendium of Weeds as an agricultural and environmental weed (Randall, 2012). The species is native to tropical America and Africa and listed as invasive in Cuba, India, Australia and Hawaii.
M. aegyptia is a relatively common weed in sugarcane (Brazil, Lesser Antilles, Reunion) and maize fields (Guatemala, Brazil, Nigeria), where it climbs up plants, bending and entangling their stems (Standley and Williams, 1970;Fournet and Hammerton, 1991;Lima e Silva et al., 2004;Valery, 2006;Chikoye et al., 2009;Correia et al., 2010;Correia, 2016). It has also been reported in cotton (Cardoso et al., 2010), banana (Isaac et al., 2009), rice (Ismaila et al., 2015), green pepper (Coelho et al., 2013), muskmelon (Teófilo et al., 2012), yam (Fournet and Hammerton, 1991) and coffee plantations (Gavilanes et al., 1988).
The following information is adapted from Holm et al. (1977);Kostermans et al. (1987);Waterhouse and Norris (1987);Henty and Pritchard (1988);Parsons and Cuthbertson (1992) and Noda et al. (1994).
M. diplotricha is a scrambling, strongly branched shrub growing 1-2 m tall, woody at the base with age, with stems stretching to about 6 m long, forming low, tangled masses or climbing on other vegetation with the aid of its spiny stems. The green or purplish tinged stems are 4- or 5-angled in cross-section and covered with abundant sharp, recurved, yellowish spines, 3-6 mm long, on the angles and fine, white hairs. According to Henty and Pritchard (1988) the stems do not root above the base, but according to Kostermans et al. (1987) they do. The root system has a robust and branching taproot extending to 1-2 m in depth and often woody at the crown. There are characteristic rhizobial nodules on the root hairs.
The scattered bright-green leaves are finely bipinnate and 10-20 cm long. The leaves consist of 4-9 pairs of pinnae, 3-6 cm long, each with 12-30 pairs of opposite, sessile, lanceolate, acute leaflets, 6-12 mm long and 1.5 mm wide. The leaflet pairs fold together when touched and at nightfall, but they are considered as only moderately sensitive. The rachis is thickened at the base with slender, tapering stipules, and finely hairy with a few prickles along the back.
The flowers are pinkish-violet in colour and occur in globose heads about 12 mm in diameter, singly, in pairs or threes on individual stalks originating in the axils of young leaves. The peduncles are 6-10 mm long and hairy. The corolla is 2 mm long, regular, 4-lobed and green at the tips, with 8 pinkish-violet exserted stamens. The flat, softly spiny, linear, 3-6 seeded pods are 10-35 mm long, 6-10 mm wide, occur in clusters in the leaf axils and break into 1-seeded joints which fall away from unbroken sutures. The seeds are yellow-brown, glossy, flattened, ovate and 2-3.5 mm long. There is a horseshoe-shaped ring on each face. The plant reproduces only by seed.
M. diplotricha (syn. M. invisa) is a small, often scrambling, neotropical shrub that has invaded many countries in the old tropics and many oceanic islands. In recent decades it has spread to new regions and has the potential to invade more tropical areas. It forms impenetrable spiny thickets that invade highly disturbed sites, but agricultural systems in particular. The shrub produces large quantities of seeds at an early age and has a persistent seed bank. It is extremely difficult to control effectively using mechanical or chemical means, however, biological control programmes have had a large degree of success.
M. diplotricha is the principal weed of rubber and coconut in Papua New Guinea, rubber in Indonesia, sugarcane in Taiwan and the Philippines, lychee in Thailand, and tomato in the Philippines. It is considered a weed of sugarcane in Australia and India;cassava, soyabeans, maize, apple, citrus and tea in Indonesia;coconut in Sri Lanka;rubber in Malaysia;banana and tea in India;and abaca (Musa textilis) and pineapple in the Philippines (Wong, 1975;Holm et al., 1977;Tea Research Association, 1977;Aliudin and Kusumo, 1978;Taepongsorut, 1978;Mendoza, 1979;Suwanarak, 1988;Groves, 1991;Muniappan and Viraktamath, 1993). It is also considered a major threat to tropical pastures in Australia (Groves, 1991;Willson and Garcia, 1992), the Pacific islands (Swarbrick, 1989;Willson and Garcia, 1992), Papua New Guinea (Henty and Pritchard, 1988) and the Philippines (Holm et al., 1977). It is a weed of lowland rice in Indonesia, the Philippines, Thailand and Vietnam;of dry-seeded rice in the Philippines;and of upland rice in Indonesia, Laos, the Philippines, Thailand and Vietnam (Kostermans et al., 1987;Moody, 1989). It is potentially the worst weed in plantations and arable lands of Fiji and the Philippines (Holm et al., 1977). It is also a weed of betelnut palm, arabica coffee, apples, cassava, banana and tobacco.
Herbs 10-20 cm tall, annual or perennial, creeping, sprawling, prostrate, or decumbent. Stems villous, often rooting at nodes. Petioles 0.2-3 (-4) cm, villous;leaf blade elliptic to ovate, 1-2 × 0.4-1.2 cm but basal ones sometimes 6-12 × 3.5-5 cm, both surfaces villous, base cuneate, margin entire, apex acute. Spikes 1.5-4 cm long;bracts elliptic, overlapping, 6-7.5 × 3-4 mm, 5-7 veined. Calyx abaxial lobe approximately 2 × 0.6 mm, apex 2-lobed;adaxial lobe approximately 3 × 1 mm;lateral lobes approximately 2 × 0.5 mm. Corolla bluish purple or white, externally glabrous;tube cylindric for approximately 1.5 mm, contracted near midpoint then expanded into throat;lower lip approximately 2.3 mm;upper lip approximately 2 mm. Stamens inserted at base of throat;filaments 0.5 mm, glabrous. Ovary glabrous with 4-8 ovules per locule. Fruit a capsule of approximately 5 × 2 mm, 8 to 16 seeds. Seeds broadly ellipsoid and granulate (Flora of China Editorial Committee, 2014).
N. canescens has been recorded growing as a weed in rice, maize, melon, and oil palm plantations (Ekeleme and Chikoye, 2003;Essandoh et al., 2011;Mahbubur, 2013).
P. foetida is a branched annual or perennial herbaceous vine 1-5 m tall with an annual or perennial woody tap root. Most parts of the above ground plant carry distinctive glandular hairs, the tips of which secrete a distinctively odorous substance. The plant scrambles or climbs by means of tendrils, and spreads only by seed.
Stems 1-5 m long, branched, herbaceous, round, green and finely hairy.
Leaves single, alternate, stipules to 1 cm long and divided into hair-like segments, petiole 2-10 cm long without nectary glands, blades 5-15 cm long, 3 or 5 lobed, the base cordate, the edges generally fringed with glandular hairs, the veins prominent, pale green and often finely hairy.
Tendrils leaf-opposed, unbranched, coiling and grasping.
Flowers solitary in upper leaf axils, peduncle 3-5 cm long, bracts 2-4 cm long and deeply divided into hair-like segments that surround the flower and fruit, sepals 5, greenish petals 5, blunt, white to pale purple or pinkish, 3-5 cm across surrounding a 2-rowed corona of purplish filaments, 5 stamens spreading at the top of a column, styles 3.
Fruits oval, 2-3 cm long, smooth, enclosed in hairy bracts. At first fleshy and green, maturing dry and yellow or orange to red, sometimes spotted, even pale green (Amela Garcia, unpublished data).
Ripe seeds blackish, flattened, wedge-shaped, 3-4 mm long, irregularly ridged, surrounded by a transparent aril.
Seedlings with epigeal germination. Hypocotyl 8-12 mm long, hairless, light green. Cotyledons shortly stalked, oblong, light green, 8-12 mm long, hairless, strongly veined. Juvenile leaves single, ovate, irregularly lobed, 12-14 mm long, with glandular hairs on margins and stalks. Seedlings foetid when crushed.
The following summary is from Witt and Luke (2017)
P. foetida occurs in a very wide range of crops, pastures and plantations.
Herbaceous vine, much branched from the base, climbs by means of tendrils and attains 1.5-2 m in length. Stems with 5 longitudinal ribs, glabrous or puberulent;cross section with a single vascular cylinder. Leaves alternate, biternate;leaflets chartaceous, puberulent or sparsely pubescent, the apex obtuse, acute, or acuminate, the base attenuate, the margins lobate or laciniate;terminal leaflet lanceolate or triangular, rhombic or narrowly lanceolate in outline, 2-3.5(5) cm long;lateral leaflets ovate, lanceolate, or oblong in outline, 1-2.5 cm long;rachis and petiole not winged;petioles 2-3 cm long;stipules lanceolate, approximately 5 mm long;tendrils in pairs, spirally twisted, at the end of short axillary axes (aborted inflorescences), from which an inflorescence usually develops. Flowers functionally unisexual, zygomorphic, in axillary racemiform thyrses, shorter than the accompanying leaf. Calyx light green, of 4 unequal sepals, the outer ones approximately 1.2 mm long, the inner ones 3-3.5 mm long. Petals white, obovate, 2.5-3.5 mm long;petaliferous appendages slightly shorter than the petals, fleshy and yellow at the apex, forming a hood that encloses the apex of the glands of the disc;disc unilateral, with 4 rounded or ovoid glands, approximately 0.4 mm long;stamens 8, the filaments unequal, pubescent;ovary trilocular, with one style and 3 stigmas. Capsules brown, pearlike, turbinate-obtriangular or sometimes nearly ellipsoid, 1.5-3 × 2-4 cm, pubescent. Seeds black, shiny, approximately 5 mm in diameter;hilum green when fresh, white when dry, cordate (Acevedo-Rodríguez, 2005;Flora of China Editorial Committee, 2015).
C. halicacabum is a long-lived scrambling, creeping, or climbing vine that is a weed of gardens, roadsides, disturbed sites and plantations. It has also the ability to climb and cover mature trees up to 8 m or more in height (Weeds of Australia, 2015). This species is often cultivated as an ornamental in gardens of tropical and subtropical regions of the world for its inflated balloon shaped fruits (Acevedo-Rodríguez, 2005;PIER, 2015;PROTA, 2015;Weeds of Australia, 2015). It has escaped from cultivation, and once naturalized it grows over native vegetation smothering trees, shrubs and understory vegetation. It is very successful invading forest margins, woodland, grassland, riverbanks, floodplains and rocky sites. Dense infestations can also impede access, increase the risk and intensity of fires and harbour pests and diseases (Invasive Species South Africa, 2015). Currently, C. halicacabum is regarded as a weed and invasive species in Australia, South Africa, Kenya, Tanzania, Uganda, French Polynesia, the Cook Islands, New Caledonia, Singapore, the USA, and Cuba (Foxcroft et al., 2003;Oviedo Prieto et al., 2012;BioNet-EAfrinet, 2015;PIER, 2015;USDA-NRCS, 2015;Weeds of Australia, 2015).
C. halicacabum is a weed with substantial economic impacts on sugarcane and soyabean plantations (Gildenhuys et al., 2013).
Herbaceous, twining or creeping vine, attaining up to 6 m in length. Stems cylindrical, glandular- pubescent. Leaves alternate, 5-palmately compound;leaflets 1.5-7.5 x 0.7-3.5 cm, elliptical, ovate or ovate-lanceolate, the apex obtuse, the base acute or decurrent, the margins entire, undulate or dentate, glabrate or glandular-pubescent on both surfaces. Flowers in simple or double dichasial cymes;peduncles longer than the petioles;bracts persistent, linear to subulate;sepals subequal or unequal, 1-1.5 cm long, ovate to ovate-lanceolate, acuminate at the apex, glandular-pubescent;corolla funnel-shaped, white or sometimes pink, with or without a purple centre, 1.5-3 cm x 3-4 cm;stamens 5, white, sometimes with lilac anthers;stigma bilobed, white. Fruit capsular, 4-valvate, globose, 6-8 mm in diameter, light brown, glabrous, surrounded by the persistent sepals. Seeds 4 per fruit, ellipsoid, 5-6 mm long, dark brown, lanate (Acevedo-Rodríguez, 2005;Austin et al., 2012).
Merremia cissoides is a climbing weed native to tropical America that has been introduced to several Old World countries, presumably as an ornamental. It typically grows in disturbed areas and has been reported as a weed of several crops within its native range. However, it is not as widespread and common as other weedy species of Merremia. In several countries outside its native range, its occurrence has only been documented from one or few herbarium specimens. Nonetheless, the species is considered to be increasingly naturalized in the Old World tropics. It is invasive in Florida (USA) and Cuba.
The species has been reported as a weed of sugarcane fields in Brazil (Perim et al., 2009;Correia and Kronka Júnior, 2010) and has also been reported in maize (Tavella et al., 2015), soybean (Timossi and Durigan, 2006), eucalyptus (Carbonari et al., 2010) and coffee plantations (Gavilanes et al., 1988).
This description was taken from the Flora of China Editorial Committee (2018)
Sonchus asper is an annual herb considered native to Europe, Africa and Asia that has been introduced to a wide range of countries around the world, where it frequently becomes an environmental and agricultural weed. The species grows in a wide range of habitats and climates, and produces large numbers of seeds (20,000 seeds), which are easily dispersed by wind and water, but also as contaminants. Because S. asper is very successful colonising disturbed sites, as well as natural habitats at early successional stages, it has the potential to outcompete native plant species, inhibit the establishment of other native pioneer species and thus alter natural successional processes. It is also regarded as a noxious species due to hosting diseases and pests that affect crops.
S. asper has been listed as a weed of alfalfa, cotton, coffee, beans, garbanzo beans, tomato and maize plantations (Villaseñor and Espinosa, 1998;Vibrans, 2009).
Annual herb, up to 4 m tall. Stems at first densely pilosulous with short hairs, in age glabrate;leaves alternate, petiolate, the blades rather thin, ovate to triangular-ovate, mostly 7-20 cm long, acuminate, cuneate (or sometimes almost truncate) at the base and then contracted and decurrent on the petiole, simple or sometimes trilobate, the margins serrate, hispid-pilose on both surfaces, especially on the veins, scabrous, glandular-punctate beneath;heads long-pedunculate;involucres 2-3 cm broad;phyllaries biseriate, 1.5-2.5 cm long, subequal or graduate, the outer ones lance-oblong to ovate-oblong, acute or acuminate, finely pilosulous, the herbaceous apex often lax or reflexed, the inner phyllaries similar but usually shorter;ray flowers 9-13, the ligules golden yellow or orange, 2-3 cm long;disc flowers yellow, the corollas puberulent, about 9 mm long;pales acuminate to cuspidate, hispidulous above, 12-18 mm long;achenes more or less appressed-pilose or glabrous, 6-7 mm long;pappus awns 2, early deciduous, or those of the outermost flowers sometimes wanting, 3-6 mm long, the squamellae united nearly to the apex, irregularly dentate, about 2 mm long (Nash, 1976).
Tithonia rotundifolia is an herbaceous flowering plant that has been widely introduced as an ornamental and has escaped from cultivation to become invasive mostly in ruderal areas, roadsides and in disturbed sites near cultivation. In this species, traits such as its rapid growth rates, abundant production of seeds that are easily dispersed by wind, water and animals, and high germination and recruitment rates are contributing to its invasiveness and allow it to quickly invade new habitats and survive even under less favourable conditions. T. rotundifolia forms dense stands with negative impact on native biodiversity as they outcompete and displace native vegetation, alter natural regeneration and obstruct access to riverbanks (Mawela, 2014;BioNET-EAFRINET, 2018;ISSA, 2018).
T. rotundifolia is a weed of beans, chickpeas, tomato, and maize plantations. It is also listed as a weed of apple orchards and citrus plantations (Villaseñor and Espinosa, 1998;Vibrans, 2009).
P. suberosa is a herbaceous vine that clings to other vegetation by means of tendrils. The striated angled stems are glabrous or pubescent with corky bark. The leaves are highly polymorphic but tend to be deeply 3-lobed, 2.8-10.7 cm long (at most 14 cm) and 1.4-4 cm wide (at most 9 cm);sometimes entire rather than 3-lobed with 0.3-1.5 cm petioles, 2 paired-stalked 1 mm nectaries;the 3-4 mm stipules are linear-lanceolate. The white campanulate flowers with purple base are without petals, 0.5-2.4 cm in diameter with 5 greenish-yellow or white sepals. Peduncles (usually paired) are 0.9-1.7 cm long with a 1 mm hypanthium. Globose berries are 0.6-1.9 cm in diameter (about the size of a pea), and dark purple when ripe (Wagner et al., 1999). Individual vines tend to grow 60 cm or longer, but the plant can grow 6 m tall (Gann et al., 2011;Invasive Species South Africa, 2013).
P. suberosa is a herbaceous vine that clings to other vegetation by means of tendrils. Native to South and Central America, P. suberosa has become invasive on Pacific Islands in Melanesia and Hawaii and is also extending its invasive range through parts of Southeast Asia, Australia, India and Africa. (Its purple fruits are attractive to birds, which serve as vectors for its spread. As an herbaceous vine, it grows rapidly, smothering and competing with native vegetation, particularly in the sub-canopy (Biosecurity Queensland, 2007). Although its growth and rate of spread does not match the more aggressively growing Passiflora species, such as P. mollissima or P. foetida, it is nonetheless increasingly recognized as an undesirable weed through its damage to native forest species (Richardson, 2007;Bohm, 2012). It has also been recorded as invading sugar cane and Eucalyptus plantations (Seeruttun et al., 2005).
P. suberosa is capable of smothering large trees (Mootooka et al., 2003). Although primarily an environmental weed, it has been reported to invade sugar cane and Eucalyptus plantations (Seeruttun et al., 2005). Despite not being as serious an invader as the congeneric P. mollissima (banana poka), P. suberosa can smother other native forest plants, and the thick, corky stems can impose additional weight on plants infested by the climber (Bohm, 2012).
P. alliacea is a herbaceous plant, stems erect, up to 1 m tall, pubescent to glabrate. Leaves are alternate, simple and entire, stipules 2 mm;petiole 0.4-2 cm;blade elliptic to oblong or obovate, to 20 × 7 cm, base acute to cuneate, apex acuminate or acute to obtuse or rounded. Leaves and stems with garlic smell. Inflorescences often drooping distally, 0.8-4 dm;peduncle 1-4 cm;pedicel 0.5-2 mm. Flowers are bisexual, zygomorphic, slightly imbricate to rather remote;sepals white or greenish to pinkish, linear-lanceolate to linear-oblong, 3.5-6 mm;ovary superior. Fruits are narrowly oblong achenes subtended by persistent bracts and perianth, 6-8 mm long, striate with recurved hooks, 1 seed (Nienaber and Thieret, 2003;Alegre and Clavo, 2007).
P. alliacea is a herbaceous perennial herb, with medicinal properties, included in the Global Compendium of Weeds (Randall, 2012). Within its native distribution range, this species is a common weed in pastures, agricultural lands, waste areas, roadsides, and riverbanks. It is listed as an “agricultural weed” in Mexico, Cuba, Colombia, Brazil, Puerto Rico, and Central America where it affects mainly coffee and maize plantations (Cardenas and Coulston, 1967;Garcia et al., 1975;Más and Lugo, 2013). Seeds of P. alliacea can be easily dispersed at local and long-distances attached to animals’ fur and feathers and human clothes by spiky hooks and barbed projections present in the fruits (Mori and Brown, 1998;Nienaber and Thieret, 2003). The species is a fast-growing herb with a wide environmental tolerance which may aid its survival as a successful weed.
P. alliacea is considered an “agricultural weed” in coffee, maize, and apple plantations in Mexico, Cuba, Colombia, Brazil, Puerto Rico, and Central America. It is also listed as a weed in pasturelands and secondary forests (Cardenas and Coulston, 1967;Garcia et al., 1975;Más and Lugo, 2013).
T. alata is an herbaceous vine, creeping or climbing, twining, 2-3 m in length. Stems cylindrical, slender, puberulous. Leaves opposite;blades 4.5-10.5 × 3.2-6 cm, ovate, lobed, chartaceous, the apex acute, the base subcordiform;upper surface dark green, dull, pubescent;lower surface pale green, dull, with prominent venation;petioles 4-8 cm long, winged, pubescent. Flowers axillary, solitary;pedicels pubescent, 4-5 cm long;bracts green, ovate, pubescent, 1.5 cm long, covering the calyx and the corolla tube. Calyx yellowish green, with 12 filiform lobes, approximately 4 mm long;corolla orange, pale yellow, or less frequently whitish, infundibuliform, with 5 lobes, the tube approximately 2.5 cm long, narrow at the base, dark violet inside, the lobes approximately 2.5 cm long with the apex truncate, the limb approximately 5 cm in diameter;stamens with glandular hairs on the basal portion. Capsules approximately 4 mm long, depressed-globose to 4-lobed at the base, the upper half in the form of a beak, dehiscent by two valves;seeds 2 or 4, 1.2-1.5 mm long, semicircular, reticulate (Acevedo-Rodríguez, 2005). Several cultivars have been developed, including some with white, yellow, and even pinkish-coloured flowers (Queensland Department of Primary Industries and Fisheries, 2011).
T. alata is an herbaceous vine, often cultivated as an ornamental, which has escaped and naturalized mostly in disturbed areas in tropical, subtropical and warmer temperate regions of the world (Starr et al., 2003;Meyer and Lavergne, 2004;Queensland Department of Primary Industries and Fisheries, 2011). It is a fast-growing vine with the capability of reproducing sexually by seeds and vegetatively by cuttings, fragments of stems and roots (Starr et al., 2003;Vibrans, 2009). Once established, it completely smothers native vegetation by killing host-trees, out-competing understory plants, and negatively affecting the germination and establishment of seedlings of native species (Starr et al., 2003;Meyer and Lavergne, 2004). T. alata is included in the Global Compendium of Weeds (Randall, 2012) and it is also considered an aggressive invasive plant in Australia, Japan, Singapore, Costa Rica, Cuba, Puerto Rico, Brazil, Colombia, Paraguay, and numerous islands in the Pacific including Hawaii and French Polynesia.
T. alata is considered a weed affecting mostly plantation crops such as Citrus, coffee, mango, and banana plantations (Vibrans, 2009).
The form of P. cattleianum trees depends on the environment. In full sunlight, it is a slow growing evergreen shrub, 2–4 m tall and often branching from the base with an overall round shape. Under shaded conditions, P. cattleianum is erect and branches weakly and can reach 8 m tall.
The slender stem and branches are smooth, pinkish, greenish or greyish brown in colour. Bark peels off in small papery flakes. Twigs are glabrous and cylindrical, and young leaves and twigs are red in colour. Leaves are opposite and decussate, shortly petiolate (petiole 3–10 mm long), elliptic to obovate, 4.5–12 cm long and 2–6 cm wide, with a blunt to slightly acuminate apex and a cuneiform sharp base. They are thick and coriaceous, upper surface dark green in colour, glossy, waxy, flat or slightly folded around the main rib. The lower surface is glabrous, whitish-green in colour, punctuated with small oil cavities (Arruda and Fontenelle, 1994), with the main rib prominent near the base but the 8–10 pairs of lateral ribs are not prominent, forming an intra-marginal rib 1–3 mm from the edge of the limb. Young leaves and twigs are red in colour.
The fragrant flowers are axillary and solitary, rarely grouped in 2 or 3. The four to five white petals are obovate, 5–6 mm long and wide. Flowers bear numerous stamens, 256 to 480 according to Raseira and Raseira (1996), and a greenish disc-shaped stigma. Ovary is tri- to pentalocular, mostly tetralocular. Fruit is a globulous to obovoid berry, 1.5–4 cm in diameter, bearing persistent sepals at the apex. The thin skin is dark green when unripe, and then red to purple for P. cattleianum var. cattleianum and sulfur-yellow for P. cattleianum var. lucidum. Pulp is soft, whitish, and contains several (2–100) seeds (Huenneke and Vitousek, 1990;Raseira and Raseira, 1996;Normand, 2002a). Seeds are reniform, 2–3 mm long, with a yellowish testa. Fruit has a pleasant, strawberry-like flavour when ripe, hence its common name.
The use of remote sensing to map the introduction and spread of P. cattleianum in Hawaiian forests has been investigated (Barbosa et al., 2016). Use of airborne imaging spectroscopy followed by classification with a Biased Support Vector Machine framework is suggested as showing promise for detecting P. cattleianum invasion.
P. cattleianum is naturalized in many tropical and subtropical countries after introduction as an ornamental or a fruit tree. It has invaded humid areas such as rainforests on tropical islands especially in the Pacific and Indian Oceans where it displaces native species and threatens their survival. It thrives in a large range of ecological conditions and reproduces efficiently by seeds and suckers. Once established, it forms dense stands. This species shows allelopathic activity and its fruits host fruit flies (Motooka et al., 2003). Seeds continue to be available via mail-order on websites or seed catalogues, and the species will likely spread further.
P. cattleianum is not a weed of crops but is an invasive species which threatens native forests and forestry plantations, and which has invaded meadows and pastures crowding out desirable forage plants (Hosaka and Thistle, 1954).
The following description is from the Flora of China Editorial Committee (2017)
Medicago lupulina is an annual or short-lived perennial herb with a wide native range across Africa, Asia and Europe. It is a common weed in disturbed areas, wastelands, roadsides, abandoned pastures and forest margins. It is a nitrogen-fixing species cultivated for forage and used as a soil improver;it is also a seed contaminant of other crops. Currently, it is listed as invasive in the Philippines, Hawaii, New Zealand and a small number of islands in Oceania. However, there is limited information available about its environmental impact in these locations.
M. lupulina is listed as an agricultural weed of alfalfa, maize plantations and apple orchards (Vibrans, 2009).
The following description is taken from Flora of China Editorial Committee (2015):
Annual grass, culms tufted, erect or geniculately ascending, slightly flattened, 15–100 cm tall. Basal leaf sheaths strongly keeled, glabrous;leaf blades flat or folded, 5–30 cm, 2–7 mm wide, glabrous, adaxial surface scabrous, apex acuminate;ligule 0.5–1 mm, glabrous or ciliate. Racemes digitate, 5–12, erect or slightly slanting, 2–10 cm, silky, pale brown or tinged pink or purple;rachis scabrous or hispid. Spikelets with 2 or 3 florets, 2-awned;lower glume 1.8–2.2 mm;upper glume 3–4 mm, acuminate;lemma of fertile floret obovate-lanceolate in side view, 2.8–3.5 mm, keel gibbous, conspicuously bearded on upper margins with a spreading tuft of 2.5–3.5 mm silky hairs, margins, keel and flanks silky-ciliate or glabrous;awn 5–15 mm;second floret sterile, oblong, glabrous, awn 4–10 mm;third floret occasionally present, reduced to a small clavate scale, awnless.
Chloris virgata is a widespread and very variable weedy annual grass (Flora of China Editorial Committee, 2015). This species is a particularly aggressive invader of bare areas and degraded or disturbed native vegetation, and it has the potential to out-compete native vegetation in these habitats (Smith, 2002;Oviedo Prieto et al., 2012;Weeds of Australia, 2015). This weedy grass spreads from cultivation, pastures, gardens, disturbed areas and roadsides to nearby disturbed forest, creeks and riversides, native grasslands and coastal habitats such as coastal forests and sand dunes (Weeds of Australia, 2015;FAO, 2015;PIER, 2015). It also grows as a weed in agricultural lands (Vibrans, 2009). Currently, this species is regarded as an invasive and environmental weed in northern Australia (i.e., Queensland and the Northern Territory;Weeds of Australia, 2015) and as an invasive grass in Cuba, Palau, New Caledonia, the Galapagos Islands, and Hawaii (Wagner et al., 1999;Charles Darwin Foundation, 2008;Oviedo Prieto et al., 2012;PIER, 2015).
C. virgata is a common weed in alfalfa (Medicago sativa) fields of the southwestern USA (Barkworth, 2003) and maize and sorghum plantations in Mexico (Vibrans, 2009).
Twining vine. Stem glabrous, not producing tubers. Leaf blades 2-8.5 × 1-5 cm, elliptic, at base rounded to cuneate, at apex acute to shortly acuminate. Inflorescences 4 - 25(- 35) cm long, unbranched or rarely with few (to many) branches, often with rather stout axis. Pedicels 1-3 mm long. Bracteoles persistent, triangular to very broadly ovate or almost circular, usually free. Flowers bisexual. Sepals 2.5-3.5 × 2-2.5 mm, usually shorter than petals, rarely equalling them in length, patent, ovate to elliptic, at anthesis whitish or cream-colored, in fruit brown. Petals 3-4 × 1-2 mm, uniform, more or less patent at anthesis and more or less erect in fruit, elliptic to obovate, at anthesis whitish or cream-colored, in fruit brown. Anthers at least sometimes pale reddish. Style 1, undivided. Fruit completely surrounded or loosely enclosed by persistent, more or less erect petals (Eriksson, 2007).
A. baselloides is an invasive succulent vine capable of smothering and destroying native vegetation. Currently, this species is regarded as an environmental weed in the Dominican Republic and as an agricultural weed in Sri Lanka where it is impacting tea plantations (Ranamukhaarachchi et al., 1997). The species has climbing stems which can totally envelop the canopy layer, reducing light penetration and eventually killing the plants beneath and preventing the germination and regeneration of native plants.
A. baselloides has been reported as an agricultural weed impacting tea plantations in Sri Lanka (Ranamukhaarachchi et al., 1997).
P. chinensis is a perennial herb. Rhizomes stout. Stems erect, 70-100 cm tall, ligneous at base, much branched, striate, glabrous or retrorsely hispid. Petiole 1-2 cm, usually auriculate at base, upper leaves subsessile;leaf blade ovate, elliptic, or lanceolate, 4-16 × 1.5-8 cm, both surfaces glabrous or hispid, abaxially sometimes pubescent along veins, base truncate or broadly cordate, margin entire, apex shortly acuminate;ocrea tubular, 1.5-2.5 cm, membranous, glabrous, much veined, apex oblique, not ciliate. Inflorescence terminal or axillary, capitate, 3-5 mm, usually several capitula aggregated and panicle-like;peduncle densely glandular hairy;bracts broadly ovate, each 1-3-flowered. Perianth white or pinkish, 5-parted;tepals ovate, accrescent in fruit, becoming blue-black, fleshy. Stamens 8, included. Styles 3, connate to below middle. Achenes included in persistent perianth, black, opaque, broadly ovoid, trigonous, 3-4 mm (Flora of China Editorial Committee, 2014).
P. chinensis is closely related to other important invasive Persicaria species such as P. orientalis, P. capitata, and P. perfoliata, all species included in the Global Compendium of Weeds (Randall, 2012). P. chinensis is a fast-growing herb that forms dense mats and tolerates diverse environmental conditions (Galloway and Lepper, 2010). It spreads by seed and by resprouting from broken fragments. Its high growth rates and spread potential provides this species the ability to smother other plants affecting plant community structure and composition (USDA-APHIS, 2012). Biosecurity New Zealand described the species in a risk assessment as “a highly invasive plant that quickly smothers available surfaces including other plants and trees,” and PIER (2014) lists it as invasive in several territories, including Hawaii.
P. chinensis is a common weed requiring control in tea plantations where it covers tea bushes and blocks drainage systems (Tjitrosemito and Jaya, 1990).
Herbaceous vine, twining, 2-3 m in length. Stems cylindrical, slender, pilose or hirsute.
I. purpurea is an annual, fast growing vine widely introduced throughout the tropics where it has become naturalized and invasive. This species has a weedy behaviour that facilitates it to colonize new areas. It is included in the Global Compendium of Weeds, where is listed as an agricultural and environmental weed (Randall, 2012). In cultivated areas, the occurrence of I. purpurea results in reduced yield, along with causing difficulties during harvesting of crops (Vibrans, 2009). In ruderal areas, disturbed sites, and natural forests, it behaves as an environmental weed which has the potential to outcompete native species for nutrients, water and sunlight. It climbs using other plants for support, and grows forming a dense canopy that shades out native vegetation. I. purpurea is listed as invasive in Australia, South Africa, Namibia, Spain, China, the United States, Cuba and the Dominican Republic (Randall, 2012;Oviedo Prieto et al., 2012;Flora of China Editorial Committee, 2014;PIER, 2014;University of Queensland, 2014). It is also separately reported as present/naturalized in Malawi and as invasive in Ethiopia.
I. purpurea grows as an agricultural and environmental weed. It is listed as a common weed in maize plantations (Vibrans, 2009). In Mexico, it has been recorded as a weed in cotton, coffee, sugarcane, peppers, beans, tomatoes, potatoes, sorghum, soyabeans and fruit orchards (Vibrans, 2009).
V. villosa is a hairy, occasionally climbing, annual plant (sometimes biennial or perennial) reaching up to 150 cm in height. It has paripinnate compound leaves ending in a ramified tendril, with 5-12 pairs of narrowly elliptical leaflets;stipules eglandular. Papilionaceous flowers (butterfly-like corolla) are blue, violet, purple, or rarely white. The corolla is 10-20 mm and the limb of the standard is nearly half as long as the claw;the calyx gibbous at the base. The inflorescence is a dense raceme with 7-22 flowers;inflorescence peduncle equal or longer than the subtending leaf. The fruit is an elliptic legume 20-40 x (4-)6-12 mm, and brown when mature. There are 2-8 seeds per pod, 3 mm in diameter, often with a hilum measuring 1/12-1/5 of their circumference.
V. villosa, commonly known as hairy vetch, is now present on all continents. It is considered as native to southern and central Europe, North Africa, West and Central Asia but its native range is difficult to ascertain because of its wide naturalization after cultivation for fodder production and as a cover crop. V. villosa usually spreads from cultivation to nearby sites where it can be self-maintained. It is a potential contaminant of crop seeds and can behave as an agricultural or environmental weed. Hairy vetch can alter habitat structure and reduce the abundance of native plants through competition for space. It can also poison mammals and poultry. In California, it has been evaluated as an invasive plant but its impacts in wildlands are considered minor (Cal-IPC, 2015).
V. villosa can be a common weed in vineyards and orchards (France, Italy), in olive (Olea europaea) plantations (Spain), and croplands;affecting maize (Zea mays) (Belgium, Portugal), grain legume crops, spring-summer vegetables (Portugal), winter crops (Belgium, Germany) and rape (Brassica rapa)(Germany) (Hyppa, 2015).
P. perfoliata is a prickly scrambling vine. It can reach a height of 6 m or more through climbing over shrubs and understory trees. The stems are elongated, branched and furrowed with short recurved prickles along the ridges. The thin, papery leaves are triangular, about 3-7 cm long and 2-5 cm wide, glabrous on the upper surface with prickles along the mid-rib on the underside (Zheng et al., 2005). The circular, saucer-shaped leafy structures, called ocrea, surround the stem at nodes. The inflorescences are capitate or spike-like racemes up to 2 cm long with clusters of 10 to 15 tiny flowers either terminal or in the axils of upper leaves (Kumar and DiTommaso, 2005). The flowers, 1-3 cm long, are borne on racemes. The fruits are attractive, deep blue and arranged in clusters at terminals, each containing a single glossy, black or reddish-black hard seed called an achene (NPS, 2009). Roots are fibrous and shallow.
P. perfoliata is a fast growing, spiny and herbaceous vine. Like many other members of the genus Persicaria, the plant is an aggressive and/or invasive weed. The plant scrambles over shrubs and other vegetation, and blocks the foliage of covered plants from available light, thus reducing their ability to photosynthesize. The leaves, petioles, and stems of P. perfoliata contain prickles, causing the movement of wildlife, and human activities to be impacted in infested areas (Okay, 1997). In its native China the plant has been used in Chinese medicine for over 300 years (Lou et al., 1988) and has rarely been recorded as an important noxious weed in either agriculture or the environment (Wang et al., 1990).
P. perfoliata is not generally a weed of agricultural land (Wang et al., 1990), as it is removed during cultivation. However, the plant can be a pest in orchards, climbing on and covering horticultural crops. In the USA, the plant has a negative effect on Christmas tree farms, forestry operations on pine plantations and reforestation of natural areas (NPS, 2009).
A stout, erect, perennial, rhizomatous grass, up to 120 cm high. Rhizomes spreading horizontally and vertically;the younger parts of the rhizome with white coherent pith and bearing yellowish-white overlapping scale leaves;the older parts yellow-brown and hollow, the scale leaves mostly perished. Roots white and fleshy when young, becoming brownish and wiry with age, up to four per node. Aerial shoots formed mainly along the vertical rhizomes, forming dense tufts;the stems of the aerial shoots form elongated internodes when buried, thus becoming vertical rhizomes. Leaves up to 6 mm wide and 60 cm long, but sometimes as much as 90 cm long, sharply pointed, usually tightly inrolled, except under moist conditions;the abaxial surface greyish-green and smooth, without distinct ribs, the adaxial surface glaucous, closely ribbed with ribs densely and minutely hairy;sheaths overlapping. Ligule up to 2.5 cm long, acuminate, split at the top when young and usually torn when older. Panicle 7-15 cm long, dense, stout, spike-like, narrowly oblong to lanceolate-oblong, tapering upwards, whitish, branches erect. Spikelets 10-16 mm long, compressed, narrowly oblong, gaping when dry, with one floret. Glumes slightly unequal, whitish, keeled, slightly pointed, margins hyaline, keel serrate, exceeding the lemma and palea;lower glume 1-nerved, upper glume 3-nerved. Lemma lanceolate, minutely rough, 5-7-nerved, keeled, 8-12 mm long, with two short points at the top, and a short stout awn less than 1 mm long in between;surrounded at the base with fine hairs c. 1/3 of the length of the lemma. Palea 2-4-nerved, compressed, acute, keeled, shortly ciliate on the keel. Lodicules c. 1 mm long, tapering. Stamens three, 4-7 mm long, up to ten times as long as wide, hanging outside the floret. Styles short. Ovary glabrous. Grains brown, obovate, shed while still enclosed by the hardened lemma and palea (Huiskes, 1979).
A. arenaria is a grass species specially adapted to growing on sand dunes. It is native to Europe and western Asia and has been introduced as a very effective sand binder to a number of other countries but has become a problem in many of these. In the countries to which A. arenaria has been introduced it invades coastal sand dunes, thriving in areas of active sand movement. In such places it not only disturbs and replaces native vegetation but can also change the topography and composition of whole foredune systems. In the USA, it has replaced the foredune vegetation, greatly reducing biodiversity, and the foredune topography has changed to much steeper slopes and whilst dune ridges further inland used to be perpendicular to the coast they are now parallel to the coast (Russo et al., 1988). In California it is negatively impacting on a number of endangered species of plants. It is reported as a major alien invader in Australia, New Zealand and South Africa where it is also having a negative environmental impact.
In North America, A. arenaria has escaped from plantations and has become naturalized north of San Francisco where it now dominates beaches formerly dominated by Elymus mollis [ Leymus mollis ] (Russo et al., 1988). Despite L. mollis being more salt tolerant than A. arenaria, A. arenaria can withstand sand accumulation of up to 1 m per year (Willis et al., 1979).
In Australia, native beach plants most commonly affected are beach spinifex (Spinifex sericeus), beach fescue (Austrofestuca littoralis), dune sedge (Carex pumila) and glistening saltbush (Atriplex billardieri). In addition to A. littoralis and S. sericeus, in New Zealand the native species affected by the spread of A. arenaria include pingao (Desmoschoenus spiralis [ Ficinia spiralis ]) and New Zealand sea spurge (Euphorbia glauca).
H. coccineum is a vigorous perennial herb. Pseudostems grow up to 1.5-2 m height. Leaves sessile;ligule 1.2-2.5 cm;leaf blade narrowly linear, 25-50 × 3-5 cm, glabrous, base subrounded or attenuate, apex caudate-acuminate. Spikes cylindric, usually dense, glabrous or sparsely villous;bracts oblong, 3-3.5 cm, leathery, sparsely pubescent, rarely glabrous, 3-flowered, margin involute or rather flat, apex obtuse or acute. Flowers red. Calyx ca. 2.5 cm, sparsely pubescent especially at 3-toothed apex. Corolla tube slightly longer than calyx;lobes reflexed, linear, ca. 3 cm. Lateral staminodes lanceolate, ca. 2.3 cm. Labellum orbicular, ca. 2 cm wide or rather small, apex deeply 2-cleft. Filament ca. 5 cm;anther 7-8 mm. Ovary sericeous, 2.5-3 mm. Capsule globose, approximately 2 cm in diameter. Seeds red. (Flora of China Editorial Committee 2012).
Hedychium coccineum is an adaptable, tall, herbaceous, and very variable ornamental plant native to Asia. It can colonise natural or semi-natural habitats, from riverine fringe and mountain grasslands to forest understorey. In its introduced range, it can become dominant or co-dominant in natural or semi-natural environments, competing with and displacing indigenous species (e.g. in La Réunion, Africa;Brazil;South Africa). Similarly to other Hedychium species (i.e., Hedychium gardnerianum and H. coronarium), it is widely traded as a garden ornamental around the world. H. coccineum is included in the Global Invasive Species Database (2014) and the Global Compendium of Weeds (Randall, 2012) and is a declared weed and invasive species in some countries. Its environmental adaptability, high commercial appeal and growing impact in countries where it has established suggest its prospective spread in delicate ecosystems cannot be underestimated.
Infestations of H. coccineum have been reported in plantations in South Africa as well as limited access to plantations caused by the plant (Henderson, 2001).
The following description is from Flora of Panama (2016)
S. linifolia is an herb or small shrub reported as invasive to Cuba and Hawaii, USA (Oviedo Prieto et al., 2012;PIER, 2016). No details are given on its invasiveness or the effects on habitats and/or biodiversity. Although it is listed as invasive for Hawaii by PIER (2016), it also is noted as “not common”.
The species occurs as a weed in cultivated land and plantations (Fariñas et al., 2011;JIRCAS, 2016). It is one of the species affected by the Okra Mosaic Virus strain, NIN-OKMV, and could be a source of infection for some crops (Igwegbe, 1983).
In Australia, E. camaldulensis commonly grows up to 20 m tall and rarely exceeds 50 m, while stem diameter at breast height can reach 1-2 m or more. In open woodlands it usually has a short, thick bole which supports a large, spreading crown. In plantations, it can have a clear bole of up to 20 m with an erect, lightly-branched crown. The bark is smooth white, grey, yellow-green, grey-green, or pinkish grey, shedding in strips or irregular flakes. Rough bark may sometimes occupy the first 1-2 m of the trunk on E. camaldulensis var. camaldulensis. This species is described in many texts including Boland et al. (1984), Brooker and Kleinig (1983, 1990, 1994), Chippendale (1988), Doran and Turnbull (1997), and Doran and Wongkaew (1997). Juvenile leaves are petiolate, ovate to broadly lanceolate, up to 26 cm long and 8 cm broad, green, grey-green, or blue-green, slightly discolorous. Adult leaves are lanceolate to narrowly lanceolate, acuminate, lamina 8-30 cm long, 0.7-2 cm wide, green or grey-green, concolorous, petioles terete or channelled, 1.2-1.5 cm long. Inflorescence axillary, 7-11 (sometimes up to 13)-flowered, flowers white, peduncles slender, terete or quadrangular, 6-15 mm long, pedicels slender, 5-12 mm long. Buds pedicellate, hypanthium hemispherical, 2-3 mm long, 3-6 mm wide, operculum globular-rostrate (typical) ovoid-conical (var. obtusa) or, in subsp. simulata, horn-shaped like E. tereticornis, 4-6 mm long (up to 13 mm long in subsp. simulata), 3-6 mm wide. Fruits are hemispherical or ovoid, 5-8 mm long and wide, disc broad, ascending, 3-5 exserted valves.
E. umbellata is a deciduous shrub 2-4 (-5) m tall and 10 cm in diameter with slender, spreading branches, more or less spiny with thorns about 2.5 cm long. The bark is removable in longitudinal strips exposing the white hardwood underneath. An important distinguishing characteristic is that shoots and young branches are clothed with very attractive white silvery scales (lepidote), but which disappear with the rains. Leaves in clusters, elliptic to ovate-oblong, 4-8 cm long and 1-2 (-2.5) cm wide, upper surface sparsely white and covered with small scaly leaves (lepidote), lower surface densely white lepidote, apex acute to sometimes obtuse, petioles 0.5-1 cm long, densely white lepidote. Fragrant flowers appear in bunches of 1-7 in axillary umbels, white to light yellow, 8-9 mm long and 7 mm in diameter, perianth densely scaled, four-lobed;androecium comprising 4 stamens, very small, attached to the mouth of the corolla tube;gynoecium, simple, with one pistil, its average length being 7 mm, pedicels 3-6 (-8) mm long, elongating up to 12 mm long in fruit;hypanthium slender, gradually narrowed at base, 5-7 mm long;calyx lobes narrowly ovate, ca 3-5 mm long. Fruits, ovoid to globose, 3-9 mm long and 5 mm broad;epicarp, thin, covering the whole fruit;mesocarp, pulpy and juicy;pedicel, 5-6 mm long;freshly picked fruits, coral pink, seeds, 7-8 mm long and 2-3 mm in diameter, saffron yellow and approximately 26 mg in weight. Adapted from PIER (2008) and Parmar and Kaushal (1982).
E. umbellata is known to invade pine plantations in the USA.
Adapted from Globinmed (2013)
Although mature A. curassavica plants are readily identified (see Description), no early detection, inspection or diagnosis methods for this species are documented. Seeds of A. curassavica do not have distinctive features, meaning that this species may be difficult to identify at inspection points. For a description of the seeds, see Description.
The milkweed A. curassica is an erect sub-shrub that is reported to be weedy or invasive across many tropical and subtropical regions of the Americas, Australia and Asia, as well as in China, South East Asia and the Pacific. The invasiveness of this species is reflected by the notably widespread scale of naturalization, together with the ease of spread and establishment of A. curassavica across a range of habitat types. Impacts of this species include the invasion of both native ecosystems and agricultural systems (e.g. Holm et al., 1997), as well as toxicity to vertebrates.
A. curassavica infestations have been reported in numerous crops species, but the impacts of this species on the growth or production of crops have not been documented. Crops affected by A. curassavica infestations include banana, coffee, cotton, mango and sorghum in Mexico;edible beans, cassava and sweet potato in Costa Rica;coconut in Cambodia;soybeans in Brazil;sugar cane in Argentina and Costa Rica, and sorghum and tobacco in Nicaragua (Holm et al., 1997). A. curassavica infestations are also reported in coconut plantations in Papua New Guinea (Peekel, 1984) and Fiji (Smith, 1988).
Habit and size
In its native range, P. patula is said to be a graceful tree, height 12-20 (30 m or occasionally to 30-40 m) with d.b.h. up to 120 cm. In plantations outside its native range, tree heights of between 35 and 50 m have been recorded, at ages ranging from 20 years to 50 years (Loock, 1950;Styles et al., 1975).
The crown shape usually depends on both spacing as well as inherent variability of the trees. Open grown trees tend to have spreading crowns while closely spaced trees tend to have narrow crowns with good suppression of lower branches which subsequently die. Some trees will still have deep narrow crowns even when growing in the open. Although branching is said to be irregularly placed on the stem (Loock, 1950), in exotic environments branching tends to be regular with on average four branches per whorl, but the distance between whorls is variable. Foxtailing occasionally occurs but the majority of trees tend to be multi nodal with average distance between whorls of about 0.4 m. Within the native distribution range, branches have been reported to be pendent whereas in exotic environments, particularly Africa, the branches are borne at an angle above the horizontal. Branch size is very variable from fine branching to very thick branches.
Stem form in P. patula is also very variable. Although atrociously crooked trees can be found in this species, stem form is generally moderate to good. Good specimen trees with straight cylindrical stems that retain apical dominance to the age of 30 years or more are quite common. Common defects include forking, sometimes caused by mechanical damage such as bird perching, butt sweep, bow, sinuosity and nodal swellings;such stem features are usually found in trees growing in warm lower altitude environments.
Bark is thick, rough and scaly with large elongated plates and deep, longitudinal fissures especially on the lower part of the bole, bark colour is dark grey-brown on lower trunk, and higher up and on younger trees bark is reddish-brown or orange, thin and papery (Vidakovic, 1991). The age at which mature bark appears is not yet known, but appears to vary with site. Some trees have been observed to develop completely smooth bark at lower, drier altitudes.
The crown may be rounded or spire-like with needles borne on pendent secondary branches. Branching may be from the ground. Young shoots are more noded, glaucous green, becoming reddish-brown in the second year.
Buds cylindrical, 15-25 mm long, covered with long pointed, fringed scales, which are not resinous and spreading at the tips. Needles are borne in fascicles of 4 (may be 3 or 5), in drooping or spreading tufts, 15 to 30 cm long, very thin, and of a shiny light to yellowish-green in colour. Stomata lines on all needle surfaces;resin ducts 2-3, usually medial, sheaths slender, persistent, 10-25 mm long. Needles may persist for two to three years.
Inflorescences, flowers and fruit
Flowering in P. patula varies from site to site. In its native range, pollen shedding begins in January and lasts until April and wide tree to tree variation is observed. In Malawi, Zimbabwe and South Africa, flowering (both male and female flowers) occurs in spring, i.e., August to October. A secondary flush of only female flowers usually occurs earlier in the year (Barnes and Mullin, 1974;Drew, 1969). In Kenya which is very close to the equator, two flushes of both flowers occur coinciding with the two rainy seasons (April-May and October-November). Female flowers have also been recorded throughout the year. In Zimbabwe, studies showed that synchronisation of pollen shedding with female receptivity is good at altitude 1500 m, whereas pollen rain became progressively later at lower altitudes.
Conelets are usually lateral, rarely subterminal, persistent, somewhat oblong, ovate-conical, curved, oblique at base, tapering towards apex, sessile, rarely subsessile, single or in clusters of 2-5, up to 10 or even more. Cone size 4-9 cm long, pale brown, hard, strong, scales oblong with raised apophyses on which there is a minute prickle. Seed triangular, grey mottled with black, 5 mm long, wing 12-18 mm long (Vidakovic, 1991;Loock, 1950).
Observations on lack of natural regeneration at lower altitudes in Zimbabwe appear to indicate that at lower altitudes seed is probably empty (infertile);at higher altitudes natural regeneration occurs. Cones, which usually take two years to mature, are harvested in September-October.
P. patula flowers as early as age 2 years with female flowers appearing first and male flowers appearing in the fourth year. Five-year old trees produce viable seeds and cone and seed production is prolific by the eighth to the tenth-year.
P. patula is a medium-size tree (usually to 20 m tall) native to eastern Mexico. It is the most important pine species in southern and East Africa (Ethiopia, Kenya, Malawi, Mozambique, Zambia, Zimbabwe, South Africa, Swaziland, Tanzania and Uganda) and is commercially planted in South America (Colombia, southern Brazil, Argentina) and, to a limited extent, in Asia (Nepal and India). The major problem of P. patula is its aggressiveness and weediness. Introduced P. patula has been found to be associated with invasion events in Hawaii (USA), South Africa, Zimbabwe, Botswana, Malawi (Haysom and Murphy, 2003) and Madagascar and New Zealand (Richardson and Rejmánek, 2004a). It is an invasive species of both fire-climax grasslands and woodland in exotic situations where climatic conditions are close to those found in its natural range.
The following description is from Flora of China Editorial Committee (2016)
S. alata is a shrub or small tree that is used as an ornamental and a cultivated plant throughout its range (Irwin and Barneby, 1982;PROTA, 2016). The species is reported as escaping from cultivation and becoming a weed in pastures, disturbed areas, orchards, plantations and shrublands (Irwin and Barneby, 1982;ILDIS, 2016). Livestock do not eat it, so the species has the potential to spread rapidly without control (ILDIS, 2016). It is reported as invasive in Asia (Hong Kong, Philippines, Singapore), East Africa and Oceania (Australia, Cook Islands, Federated States of Micronesia, Fiji, French Polynesia, Galapagos Islands, Guam, Hawaii, Palau, Papua New Guinea, Samoa and Tonga) (PIER, 2016). It is regarded as a significant environmental weed in the Northern Territory of Australia (Weeds of Australia, 2016). Risk assessments prepared for both Australia and the Pacific classed it as high risk (PIER, 2016).
C. scoparius is an unarmed leguminous shrub, having several erect or ascendant stems which can later collapse to become prostrate where crushed by snow (Hosking et al.,1998). Plants grow to 4 m high, and often form dense thickets in cooler areas. Branches are green, five-angled and mostly glabrous. Leaves are usually three-foliate, petiolate to subsessile, but one-foliate and sessile on young growth. Leaflets are narrow-elliptic to obovate, 5-20 mm long and 1.5-8 mm wide, with scattered hairs on the upper surface and numerous short hairs on the lower surface. Flowers are pedicellate, solitary or in pairs, and borne in the axils on 1-year-old stems. The calyx is glabrous, ca 6 mm long, two-lipped, upper lip with two teeth, lower lip with three teeth, all teeth usually much shorter than the lips. The corolla is golden yellow, 15-25 mm long. Fully developed pods are 2.5-7 cm long and 8-13 mm wide, oblong, dehiscent, strongly compressed, with brown or white hairs on the margin, otherwise glabrous, initially green then black at maturity. Plants are deciduous in winter in colder areas and in summer in areas with summer drought. The plant is most easily distinguished from other closely related species by its five-sided green stems, its yellow, pea-like flowers, and pea-like pods mainly 2.5-7 cm long with hairy margins (see Pictures). In the field, broom plants are conspicuous because of their dark green colour (compared to e.g. the grey-green colour of the more robust C. striatus) and especially their abundant large flowers at the peak of flowering.
C. scoparius is a perennial shrub that has been widely commercialized as an ornamental in temperate and subtropical regions of the world. It is a prolific seeder that escaped from cultivation and has become an invasive species and a serious weed in temperate areas of the United States, Canada, Hawaii, Chile and Argentina, the eastern halves of both islands of New Zealand, Australia (including Tasmania), India, Iran, Japan and South Africa (Holm et al., 1979;Parsons and Cuthbertson, 1992;Hosking et al., 1998;Peterson and Prasad, 1998;Isaacson, 2000). C. scoparius is an aggressive fast-growing invader with the capability to grow forming dense impenetrable monospecific stands that degrade native grasslands, forests, rangelands, and agricultural lands;prevent the regeneration of natural forests and prairies;and create fire hazards (Syrett et al., 1999;USDA-NRCS, 2016). Because of its association with nitrogen fixing bacteria, it is very competitive in areas with poor soils and can alter the nutrient cycling of invaded areas (Peterson and Prasad, 1998).
C. scoparius is also very common and widespread within its native range and reaches densities where it is considered a weed (Maury, 1963;Engel, 1964). Consequently, in many European countries (within its native range) it has been included in national lists of invasive species (DAISIE, 2016). However, treating this species as invasive in areas within its native distribution range is controversial as it has been present in the European flora for centuries and in many countries where it is now listed as invasive it was previously listed as native (Rosenmeier et al., 2013;DAISIE, 2016).
C. scoparius is a significant weed of forestry, particularly in pine and eucalypt plantations around the world. It either smothers planted saplings or reduces their growth (Peterson and Prasad, 1998;Barnes and Holz, 2000). In some areas, C. scoparius can be beneficial in these situations as a nurse crop protecting samplings from frost damage and other types of exposure (Peterson and Prasad, 1998), but it can also be associated with higher levels of plantation diseases (Peterson and Prasad, 1998). Once the plantation species grow above plants of C. scoparius, the impact on tree growth is minimal. In native woodland situations broom can prevent natural regeneration by shading (Hosking et al., 1998) and allelopathy (Nemoto et al., 1993).
C. pubescens is a large, erect, rapidly growing evergreen tree;up to 30 m tall, but most frequently reported as 4-10 m in height, attaining heights of 15 m on Santa Cruz, Galapagos (Shimizu, 1997);sparsely branched as lower branches shed, with young branches glabrous or pubescent. Bark brown, smooth;inner bark reddening when cut. Leaves deciduous, opposite, large, broadly elliptic-ovate to broadly oblong, 20-40 (-50) x 10-30 (-40) cm;upper surface light green, puberulent or glabrate, rather thin, membranous to papery, conspicuously veined (9-11 lateral pairs), margins entire, apex rounded, base broadly to narrowly cuneate, petioles 1.5-4.5 cm long, stipules ovate, caducous;lower surface with tufts of hairs in axils of lateral veins;old leaves reddish-orange. Flower numerous, in large panicles, rose-pink, fragrant;calyx densely appressed, pubescent, teeth deltate: heterostylous;in microstyled plants 5 exerted anthers alternate with corolla lobes and bifid stigma reaches half length of corolla tube;in macrostyled plants the situation is reversed with the stigma being exserted and the stamens hidden in pale pink corolla tube (1.0-1.2 cm long), which is villous within and comprising 5 spreading lobes, 4-5 mm long. Capsules ovoid-fusiform to oblong, 2-3 cm long;dehiscent from base to apex. Seeds 7-10 x 2-3 mm, with a broad ciliate wing. Note that this species description is a composite from several sources which vary considerably, especially in dimensions of the tree, leaves and seeds, emphasizing the variability of this species.
C. pubescens has been widely introduced throughout the tropics over the past 150 years because of its medicinal properties. However, it is only in small island systems, notably the Galapagos and Hawaii, that it has become invasive, after a relatively long period of adaptation. In the moist upland regions of these islands, it is beginning to have a significant impact on biodiversity affecting endemic species in both the flora and fauna.
C. pubescens is not a weed of agricultural crops, although there are reports of it invading Eucalyptus plantations in Hawaii (Wagner et al., 1999;Starr et al., 2003). In the Galapagos, it has invaded two of the upper vegetation zones (500-700 m), posing a threat to the endemic flora (Macdonald et al., 1988;Cronk and Fuller, 1995).
A plantation is a large-scale estate meant for farming that specializes in cash crops. The crops that are grown include cotton, coffee, tea, cocoa, sugar cane, opium, sisal, oil seeds, oil palms, fruits, rubber trees and forest trees. Protectionist policies and natural comparative advantage have sometimes contributed to determining where plantations are located.
Among the earliest examples of plantations were the latifundia of the Roman Empire, which produced large quantities of grain, wine and olive oil for export. Plantation agriculture grew rapidly with the increase in international trade and the development of a worldwide economy that followed the expansion of European colonial empires. Like every economic activity, it has changed over time.