Cyperus polystachyos Rottbøll. Coast Flatsedge. Phen: Jul-Oct. Hab: Low fields, ditches, and marshes. Dist: Pantropical and warm temperate, north in North America to ME, MA, KY, MO, and OK.
ID notes: Often difficult to separate from C. filicinus and occurring in similar habitats, although C. filicinus is generally more coastal. A highly polymorphic species; depauperate plants may resemble species in subgenus Cyperus, check carefully for 2-branched styles and biconvex achenes.
Origin/Endemic status: Native
Syn: = Ar, ETx1, FNA23, Il, NcTx, NE, Pa, Tn, Va; > Cyperus microdontus – S; > Cyperus odoratus – S, misapplied; > Cyperus paniculatus – S; < Cyperus polystachyos – GW1, WH3; > Cyperus polystachyos var. holosericeus – K4; > Cyperus polystachyos var. texensis – Bah, C, F, G, K1, K3, Mo1, RAB, Tx, W