Leersia is a genus of grasses in the family Poaceae (order Poales), comprising roughly 18 accepted species commonly known as cutgrasses. The genus has a remarkably broad distribution, with representatives found on all inhabited continents — from the wetlands of tropical Africa and the Americas to temperate Eurasia and Australasia.
Cutgrasses are typically aquatic or semi-aquatic perennial grasses that grow along the margins of rivers, streams, lakes, and marshes. They are characterized by their narrow, flat leaf blades with rough, sharply serrated edges — a feature that gives the group its common name, as the blade edges can cut exposed skin. The ligule (a small membranous flap at the junction of leaf blade and sheath) is a notable morphological feature of several species.
Among the most widespread species is Leersia hexandra, found across Africa, Eurasia, Australia, and both Americas. Leersia oryzoides (rice cutgrass) is native to Eurasia and naturalized widely in North America, where it is a common wetland colonizer. Leersia lenticularis (catchfly grass) is endemic to the central and eastern United States, while Leersia virginica (whitegrass) ranges across eastern North America. Leersia japonica is native to East Asia.
The genus was named by botanists in honor of Johann Daniel Leers (1727–1774), a German apothecary and botanist who contributed to the early systematic study of German flora. Several species formerly placed in Leersia have since been transferred to other genera including Digitaria, Hygroryza, and Arthraxon.
Etymology
The genus name Leersia commemorates Johann Daniel Leers (1727–1774), a German apothecary and botanist known for his work on the flora of the Herborn region of Germany. The common name "cutgrass" refers to the rough, serrated leaf edges that can lacerate the skin on contact.
Distribution
Leersia species are distributed across all inhabited continents. L. hexandra is pantropical, occurring in Africa, Eurasia, Australia, and the Americas. L. oryzoides spans temperate Eurasia from the Azores to the Russian Far East and is widely present in North America. African species are concentrated from West Africa east to Uganda and south to southern Africa. L. japonica and L. sayanuka are East Asian endemics.
Ecology
Cutgrasses are predominantly wetland plants, growing in shallow water, along stream banks, rice paddies, ditches, and marshy ground. Leersia oryzoides is a common colonizer of disturbed riparian habitats and can be weedy in agricultural settings. Leersia hexandra is an important forage grass for livestock and wildlife in tropical wetlands. The sharply rough leaf margins (caused by silica-tipped cells) deter some grazers while the dense stands provide cover for wetland birds and fish.
Taxonomy Notes
Several species were historically placed in Leersia but have since been reassigned: Leersia aristata is now Hygroryza aristata; Leersia digitaria is Digitaria ciliaris; Leersia hispida is Arthraxon hispidus; Leersia disticha is Megastachya mucronata; and Leersia latifolia is Maltebrunia leersioides. GBIF records 12 descendants under the accepted genus concept.
