Carex retrorsa

Carex retrorsa, (commonly known as knotsheath sedge, deflexed bottlebrush sedge, or retrorse sedge), is a widespread species of flowering plant in the family Cyperaceae, native to southern Canada and the northern United States.^[1][2]

Carex retrorsa
Seedheads remain on plant into winter, providing ornamental value
Growing in nursery flats
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Poales
Family:	Cyperaceae
Genus:	Carex
Species:	C. retrorsa
Binomial name
Carex retrorsa Schwein.
Synonyms[1]
List Carex lupulina var. gigantoidea Dewey Carex retrorsa var. gigantoides Farw. Carex retrorsa var. multispicula Lepage Carex retrorsa var. robinsonii Fernald Carex reversa Spreng.

Description

Carex retrorsa is a clump-forming, rhizomatous sedge. Leaves are bright green and smooth. Basal sheaths are generally brown to purple in colour, often splitting into a ladder shape. Inflorescence consists of multiple spikes, with the terminal spike all-staminate. Bracts are shorter than the lowest pistillate spike. Perigynia are hairless, beaked and toothed, and achenes are triangular in cross-section.^[3]

Fruit develops in late spring to summer. Pistillate spikes form clusters of seeds. Each pistillate spike contains 20 to 150 achenes.^[3]

Distribution and habitat

Carex retrorsa thrives in stream and lake shores, marshes, swamps, water meadows and alongside waterways.^[4] Preferring wet areas and tolerant of some shade, it is available from speciality nurseries for such uses as ecological restoration projects, erosion control, and rain gardens.^[5][6]