Napier grass, elephant grass
Native to: Africa
Introduced to the United States in 1913 as a forage crop, it was noted to have escaped cultivation by 1968 and as established south Florida by 1971. It can now be found in the edges of disturbed waterways, pastures, scrub, hammocks, floodplain swamp, and other wetland habitats in over half the state. It has been introduced to tropical areas worldwide because of its ability to quickly produce large amounts of biomass and is still widely used for forage used in Central America, South America, and Africa.
Taxonomic confusion: Research indicates that Pennisetum, Cenchrus, and Odontelytrum form a single group, and Pennisetum and Odontelytrum should be transferred into Cenchrus. Consequently, the accepted name is now Cenchrus purpureus however its use is inconsistent across online resources.
Habit: large perennial grass with erect stems that grow to 15 feet tall.
Leaves: flat and strap-like, up to an inch-and-a-half wide, and several feet long. They have fine-toothed margins, and sparse hairs on the leaf surface. The ligule is composed of long hairs.
Flowers: cylindrical spike at the top of the stem. It is greenish-tan, 5 to 12 inches long, and about an inch in diameter. The spike is densely packed with flowering spikelets. Many of the spikelets have very long bristles.
Distribution in Florida: throughout south and central Florida, scattered reports in northern and panhandle regions.
Napiergrass can reproduce both vegetatively and by seed. Vegetative reproduction occurs through root crown divisions or rhizome and stem fragments. Dense growth outcompetes and prevents the regeneration of native plants and it can dominate fire-adapted savannah communities. It creates problems in flood-control systems by blocking access to canals, reducing water flows, and overgrowing pump stations. It is also invasive in agricultural settings including sugar cane plantations in South Florida.
Thoroughly clean any equipment, gear, and clothing after working or recreating in infested areas.
Tilling can be used to effectively control seedling napiergrass plants. However, because of the ability of napiergrass to spread from vegetative cuttings and rhizomes, it should not be used to control mature plants and can actually cause larger infestations of napiergrass by breaking mature plants into pieces and distributing them throughout the field.
Foliar: 1–3% glyphosate product. If nontarget damage is a concern, cut stems to ground level and allow sprouts to reach 8–12 inches and treat with 5% glyphosate product. Broadcast 3–5 quarts/acre glyphosate product, 2 quarts/acre Arsenal, or 1 quart Arsenal and 2 quarts glyphosate product.
Consult your local UF IFAS Extension for further assistance with management recommendations. Additional information can be found in the EDIS Publications Integrated Management of Non-Native Plants in Natural Areas of Florida and Napiergrass: Biology and Control in Sugarcane.