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FLIP

FLIP: Florida Invasive Plants

Pennisetum purpureum

Common Name(s): Elephantgrass, napiergrass

Origin

Africa

Ecological Impact

Has created problems in flood-control systems by blocking access to canals, reducing water flows, and overgrowing pump stations (Schardt and Schmitz 1991).

Description

Robust perennial to 4 m (13 ft) tall, forming thick clumps or colonies from basal offshoots or short rhizomes. Stems often branched above; internodes more or less bluish glaucous; young nodes with white hairs, later becoming smooth, glabrous. Leaf sheaths glabrous, usually shorter than the internodes; ligule a narrow rim densely fringed with long white hairs. Leaf blades linear to tapering, flat, often bluish green, to 1 m (39 in) long and 3 cm (1 in) wide, pilose near the base, especially on margins; blade margins generally rough; midvein stout, whitish above, strongly keeled below. Inflorescence a dense terminal panicle, spike-like, bristly, tawny to purple-tinged, to about 20 cm (8 in) long and 2 cm (0.8 in) across. Spikelets 4-6 mm long, solitary or in clusters of 2-6 on hairy axis, surrounded by sparsely plumose bristles to 2 cm long that fall with the spikelets at maturity; outermost glume minute or absent.(Langeland and Burks, 1998)

Identification Tips

May be confused with the larger native foxtails (Setaria spp., also called bristle grasses), but their spikelet bristles persistent on the flowering stalks, not falling with mature spikelets. Distinguished from other Pennisetum species in Florida by long leaf blades, sparsely plumose bristles, and minute or absent first glumes. (Langeland and Burks, 1998)

History

Reported as a weed in 19 crops in 25 countries, including the United States (Holm et al. 1977). In dense growth, prevents regeneration of native species (Cronk and Fuller 1995). Can dominate fire-adapted savanna communities (Holm et al. 1977). Introduced to the United States in 1913 as a forage crop (Thompson 1919, Hoover et al. 1948). Noted as escaping in 1968 (Ward 1968), and as established in glades in south Florida by 1971 (Long and Lakela 1971).

Range

Now commonly naturalized in central and south Florida, infrequently in north and west Florida. (Langeland and Burks, 1998)

Management Strategies

Foliar: 1%-3% Roundup®. If non-target damage is a concern, cut stems to ground level and allow sprouts to reach 8-12 inches and treat the same as Neyraudia. Broadcast 3-5 quart/ acre Roundup® Pro, 2 quart/acre Arsenal®, or 1 quart Arsenal® and 2 quart Roundup® Pro.

Photos

Most photos courtesy of the Atlas of Florida Plants; click for additional plant details.

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Florida Invasive Plants