add. ·noun any of several australian grasses of the genus tricuspis, which often form dense, almost impassable growth, their leaves being stiff and sharp-pointed.
2. spinifex ·add. ·noun a genus of chiefly australian grasses, the seeds of which bear an elastic spine. s. hirsutus (black grass) and s. longifolius are useful as sand binders. s. paradoxusis a valuable perennial fodder plant. also, a plant of this genus.