P. clandestinum is a low-growing perennial grass which spreads by underground rhizomes and above-ground runners. In open situations, growth is mainly by horizontal extension of the robust runners. The runners are several mm thick, and have internodes at intervals of about 5 cm, each with a single leaf sheath and blade. The blade is bright green, 3-4 mm wide, very short;only a few cm long towards the tips of vigorous runners, but up to 15 cm long in more closed vegetation. Leaves may be glabrous or softly hairy. A tiller may or may not develop within the leaf sheath. The ligule is a short hairy rim 1-2 mm long. The inflorescences are very inconspicuous, being almost totally enclosed in leafy axillary branches, and only apparent as a result of styles or stamens protruding from their tips. The inflorescence has only 2-4 spikelets, each 1-2 cm long with 2 florets and a circle of short bristles at their base. Stigma up to 3 cm long and stamens on fine silvery filaments up to 5 cm. Seeds about 2 mm long. For further detail see Holm et al. (1977). Below ground, the rhizomes have similar morphology to the runners, but without expanded leaves, occurring at depths of 20-30 cm.
Related invasive species
- Pennisetum clandestinum
Related Farm Practice
- Thinning
- Development
P. clandestinum is an aggressive perennial plant, spreading by rhizomes below ground, especially by long runners above ground, and it also sets seed. It is native to the highlands of eastern Africa but has been widely introduced elsewhere for forage and for soil conservation. In well managed situations it does not generally spread very far but it is highly tolerant of grazing and mowing and can steadily invade poorly managed plantations. It also readily invades natural vegetation with resultant loss of biodiversity. This has occurred in Australia, New Zealand, South Africa, Hawaii and the Galapagos. It is listed as a Federal Noxious Weed in the USA.
In addition to the crops listed, many other annual and perennial crops are affected, together with pasture, turf and forestry species.