O. ramosa produces leafless flowering stems, 15-20(-30) cm high, usually very branched, bearing alternate scales, less than 1 cm long. The plant is pale, completely lacking any chlorophyll. The base of the stem, below ground, is normally swollen and tuberous. The inflorescence, occupying approximately half the length of the stems carries many acropetally developing flowers, arranged in spikes or racemes, each subtended by a bract 6-10 mm long with two additional bracteoles, attached to the base of the calyx and of similar length. The calyx has 4(-5) lobes, more-or-less deeply divided into two segments, 6-8 mm long. The corolla, 10-20 mm long, is tubular, inflated at the base, with two approximately equal lips, the lower is 3-lobed. The corolla is whitish below and cream, blue or violet distally (occasionally all white). Filaments are inserted in the corolla tube, 3-6 mm above the base. A capsule develops up to 6-10 mm long and may contain several hundred seeds, each about 0.2 x 0.4 mm. A single plant carries ten to several hundred flowers and hence may produce up to a quarter million seeds. This description is from sources including Chater and Webb (1972), and O. ramosa is dealt with in some detail in Holm et al. (1997).
Related invasive species
- Orobanche ramosa
Related Farm Practice
- Hosts
O. ramosa does not spread rapidly or aggressively but its introduction in contaminated seed or soil can go undetected, and once introduced it can cause severe damage to important agricultural crops and prove very difficult to eradicate.
O. ramosa causes no very distinctive symptoms but may cause some wilting, yellowing and necrosis of the foliage and a general weakening of the plant, with reduced fruit production.
O. ramosa has an especially wide host range, occurring on wild plants in the families Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Capparidaceae, Labiatae [Lamiaceae], Linaceae, Malvaceae, Oxalidaceae, Plantaginaceae, Polygonaceae and Rubiaceae, as well as crops in Alliaceae [Liliaceae], Compositae [Asteraceae], Cannabinaceae, Cruciferae [Brassicaceae], Cucurbitaceae, Leguminosae [Fabaceae], Solanaceae, Rosaceae and Umbelliferae [Apiaceae] (Parker and Riches, 1993). See also Qasem and Foy (2007) for a recent study of host range in O. ramosa.