Pennisetum macrourum Trin.
Family Poaceae, Tribe Paniceae
African feathergrass, waterside reed
Fascicle consists of unfused, antrorsely scabrous bristles; outer bristles number 15–20 and are 2.5–8 mm long; inner bristles number 8–10 and are 4–9 mm long; primary bristle solitary, conspicuously longer than other bristles, to 20 mm. Spikelets usually solitary, sessile or pedicellate (pedicels to 0.2 mm long), lanceolate, dorsally compressed; 2–8 mm long, ca. 1.2 mm wide; consisting of 1 fertile floret and 1 basal sterile floret (usually just the lemma). Glumes small, hyaline; lower glume absent or scale-like (to 1.4 mm long); upper glume 0.8–2 mm long. Sterile lemma membranous, 3–5(7) nerved, up to length of spikelet. Fertile lemma 3–6.8 mm long, membranous, thicker than glumes, 5–7-nerved, surface rough. Caryopsis oblong-obovate, dorsally compressed, golden; embryo up to to 3/4 length of caryopsis.
Pennisetum clandestinum Hochst. ex Chiov.
Pennisetum pedicellatum Trin.
Pennisetum polystachion (L.) Schultes.
South Africa and much of tropical Africa, Australia, New Zealand, Ascension Island and St. Helena in South Atlantic Ocean, United States
native to tropical Africa and South Africa
subhumid warm-temperate regions, wet or swampy places, along streams, roadsides, hillsides
Pennisetum macrourum is a perennial grass up to 200 cm tall, with rhizomes to a depth of 30 cm. Dense clumps may form through extensive rhizome growth. These clumps may eventually eliminate other plant species and prevent access to water. Cultivation may help spread the species, as rhizome fragments can generate roots and shoots at nodes. Disseminules may be spread by water or wind, or by clinging to animal fur. This grass has been used ornamentally as a landscape plant.
ventral view of fertile floret showing margins of lemma enclosing palea (left); spikelet subtended by primary bristle showing upper glume and fertile lemma (right).