Alloteropsis semialata, known commonly as black seed grass, cockatoo grass, donkersaad gras, swartsaadgras, tweevingergras, and isi quinti, is a perennial grass distributed across much of tropical and subtropical Africa, Asia and Australia, as well as Papuasia and Madagascar. The species has two subspecies including A. semialata subsp. semialata, which uses the C4 photosynthetic pathway, and A. semialata subsp. eckloniana, which uses the C3 photosynthetic pathway. As the only plant species known to use both pathways, it is an important model for the study of the evolution of photosynthesis.