''Heteropogon contortus'' is a tropical, perennial
tussock grass
Tussock grasses or bunch grasses are a group of grass species in the family Poaceae. They usually grow as singular plants in clumps, tufts, hummocks, or bunches, rather than forming a sod or lawn, in meadows, grasslands, and prairies. As perenni ...
with a native distribution encompassing Southern
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, southern
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...
, Northern
Australia,
Oceania
Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
, and southwestern
North America. The species has also become a naturalised weed in tropical and subtropical regions in the
Americas and East Asia. The plant grows to in height and is favoured in most environments by frequent
burning. The plants develop characteristic dark seeds with a single long
awn at one end and a sharp spike at the other. The awn becomes twisted when dry and straightens when moistened, and in combination with the spike is capable of drilling the seed into the soil.
The species is known by many common names, including black speargrass, tanglehead, ''steekgras'' (in
Afrikaans
Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their enslaved people. Afrikaans g ...
) and ''pili'' (in
Hawaiian, ultimately from
Proto-Austronesian *''pilit''₁ "to adhere/stick"). ''H. contortus'' is a valuable
pasture
Pasture (from the Latin ''pastus'', pa