Catabrosa is a small genus of perennial grasses in the family Poaceae (order Poales), described by Palisot de Beauvois in 1812. It comprises two to four species distributed across temperate regions of both hemispheres, from Eurasia and North America to southern South America and southern Africa. The plants are rhizomatous or stoloniferous, with flat, linear, glabrous leaf blades and membranous ligules. Their inflorescences are open or contracted panicles bearing small, subterete spikelets with one to three florets each. The lemmas are broadly ovate, three-veined, awnless, and have an erose (irregularly notched) apex. The florets are hermaphroditic and wind-pollinated, each with three stamens and an ellipsoid caryopsis. The chromosome base number is x = 5.
The most widespread species, Catabrosa aquatica (brookgrass or water hairgrass), is a semi-aquatic grass found across the non-tropical northern hemisphere and southern South America. It grows in wet meadows, along stream banks, and on lake shores, forming short, blunt-leaved tufts similar in appearance to Poa trivialis. Other accepted species include C. drakensbergensis of southern Africa and C. werdermannii of the southern Andes, with C. capusii recognized in Central Asian floras.
Distribution
Catabrosa species are native to temperate regions of both hemispheres. C. aquatica is the most widespread, occurring across most of the non-tropical northern hemisphere (Europe, Russia, China, Mongolia, Central Asia, Greenland, Canada, and the United States) and in southern Chile and Argentina. C. drakensbergensis is restricted to Lesotho and KwaZulu-Natal in southern Africa, while C. werdermannii occurs in the southern Andes (Chile, Bolivia, Argentina). C. capusii is recognized in Central Asian floras.
Ecology
Catabrosa species are semi-aquatic grasses that grow in consistently wet habitats. C. aquatica prefers meadows, stream banks, and lake shores. The flowers are hermaphroditic (bearing both male and female organs) and wind-pollinated. In Europe, it flowers from June to August, with seeds ripening from July to September.
Taxonomy Notes
The genus was established by Palisot de Beauvois in Essai d'une Nouvelle Agrostographie (p. 97) in 1812. Current treatments recognize two to four species, though numerous names formerly placed in Catabrosa have been transferred to related genera including Arctagrostis, Antinoria, Colpodium, Deschampsia, Glyceria, Poa, and Puccinellia. The Flora of China recognizes two species in the genus (C. aquatica and C. capusii), and gives the chromosome base number as x = 5.
