Identification: Fountain grass is currently only known to grow in a few locations in Maui County (see Maui and Lanai maps). Fountain grass is a perennial, clumping grass that can grow in a variety of habitats, from bare lava, to rangeland, to urban roadsides in drier areas of the Hawaiian islands (<127 cm rain/yr). It can reach a height of 0.2-1 m (0.5-3 ft) with bristly, cylindrical shaped purple or rose-colored flower head (100-250 mm or 4-10 in long).
Impacts: Originally introduced as an ornamental plant, fountain grass has become an aggressive habitat-invader. It degrades the quality of pasture lands, particularly in drier areas. Fountain grass is also fire-adapted and can sustain fires that spread quickly into adjacent areas. Its dried leaves increase the intensity of wildfires. After a fire it resprouts faster than native plants.
Dispersal Mechanism: Fountain grass is dispersed through the horticultural trade as an ornamental grass. Its seeds are also transported via the wind, water, vehicles, livestock, and humans. Fountain grass is a Hawaii State Noxious Weed. It is illegal to introduce or transport any part of this plant in Hawaii. It is widespread on the Big Island and Oahu, and found sparsely on Kauai in Kalaheo and Hanapepe. If you find any fountain grass in Maui, Molokai, or Lanai, or any new populations on Kauai- let us know!

More information about this pest 

Fountain grass look-alikes:

Red fountain grass (Pennisetum macrostachyum):
Red fountain grass has similar nodding, long seed heads to fountain grass, but can be differentiated by red or purple tinted foliage and seed heads. Red fountain grass also grows much taller (1.8-2.4 m or 6-8 ft).

Feathertop (Pennisetum villosum):
Feathertop is another perinneal, clumping grass that is grown in gardens with a similar growth structure and leaves to fountain grass. Feathertop produces distinctive feathery seed heads that can grow up to 90 cm (35 in) in length.