Schizachyrium is a widespread genus of grasses in the family Poaceae (order Poales), distributed across tropical and subtropical regions of Africa, Asia, Australia, Latin America, the West Indies, and North America. The genus encompasses roughly 60 to 70 species of perennial and annual tufted grasses, many of which form important components of grassland and savanna ecosystems. In the United States, members of the genus are colloquially known as bluestems — a name shared with the related genus Andropogon, reflecting their similar bluish-green foliage. The most widely cultivated and ecologically significant North American representative is Schizachyrium scoparium (little bluestem), a dominant warm-season grass of the tallgrass and mixed-grass prairies.
Morphologically, Schizachyrium species are characterized by slender culms that often have a flattened or compressed cross-section, narrow leaf blades, and distinctive racemose inflorescences borne singly at the ends of branches. The spikelets occur in pairs — one sessile and fertile, the other pedicelled and typically reduced or sterile — a hallmark feature of the tribe Andropogoneae. The genus name reflects this structure: the Greek σχίζειν (schizein, "to split") combined with ἄχυρον (achyron, "chaff") alludes to the divided or toothed nature of the glumes or lemmas.
Taxonomically, Schizachyrium is placed within the tribe Andropogoneae and has historically had an unstable circumscription. Several species formerly assigned to Schizachyrium have been transferred to allied genera including Andropogon, Dichanthium, Rottboellia, Sehima, and Sphaerocaryum. The genus has a pantropical core distribution with notable radiations in sub-Saharan Africa, and secondary diversity centers in the Americas and Australasia.
Etymology
The genus name Schizachyrium is derived from the Ancient Greek words σχίζειν (schizein), meaning "to split," and ἄχυρον (achyron), meaning "chaff." The combination refers to the split or toothed appearance of the glumes or lemmas in the flower spikelets.
Distribution
Schizachyrium has a pantropical and warm-temperate distribution spanning sub-Saharan Africa, tropical Asia (including the Indian Subcontinent and Southeast Asia), Australasia (northern Australia, New Guinea, Micronesia), Latin America from Mexico to Argentina, the West Indies, and the southern and central United States. A smaller number of species extend into Canada and into temperate parts of South America.
Taxonomy Notes
Schizachyrium belongs to the tribe Andropogoneae within Poaceae. Its circumscription has been revised repeatedly, with species formerly included in the genus now considered better placed in Andropogon, Dichanthium, Rottboellia, Sehima, and Sphaerocaryum. Multiple GBIF backbone records exist reflecting different checklist treatments; placement in Poaceae, order Poales, class Liliopsida is consistent across checklist sources.
