Cyperus odoratus Linnaeus. Common name: Fragrant Flatsedge. Phenology: Jul-Sep. Habitat: Low fields, marshes, ditches, sandbars. Distribution: Pantropical, north in North America to MA, se. ME, ON, MN, KS, NM, AZ, and CA.

ID notes: This is a widespread, weedy and highly polymorphic species, frequently confused with the equally common, widespread, and variable C. erythrorhizos and C. strigosus. In addition to the rachilla characters given in the main key, C. strigosus has cormose culm bases (vs. annual with fibrous roots) and spikelets with longer [3.2-4.5 mm vs. (2.0-) 2.2-2.8 (-3.2) mm] scales that are initially quadrangular, becoming strongly compressed at maturity; differences from C. erythrorhizos are discussed under that species.

Origin/Endemic status: Native

Taxonomy Comments: C. macrocephalus Liebm. and C. eggersii Boeckeler are striking in the field and sometimes recognized, occurring in our area in s. TX. C. macrocephalus is distinguished by inflorescences congested into a single globose capitate cluster 2-3 cm in diam., ellipsoid (vs. oblong) achenes, and sharply trigonous culms; C. eggersii by penicillate spikes with very densely fascicled, erect-appressed spikelets (vs. looser spikes, the spikelets spaced out along the rachis and divaricate).

Synonymy ⓘ: = Ar, C, ETx1, FNA23, G, GrPl, GW1, Il, K4, Mex, Mi, Mo1, NcTx, NE, NS, NY, Pa, Tat, Tn, W, WH3; > Cyperus ferax Rich. — S; > Cyperus ferruginescens Boeckeler — F, RAB; > Cyperus longispicatus Norton — S; > Cyperus macrocephalus Liebm. — Tx; > Cyperus odoratus L. — F, RAB, Tx; > Cyperus odoratus ssp. odoratus — POWO; > Cyperus odoratus ssp. trancaucasicus — POWO; > Cyperus odoratus L. var. odoratus — Va, Tucker & Gandhi (2019); > Cyperus odoratus L. var. squarrosus (Britton) S.D.Jones, Wipff, & R.Carter — Can, Tucker & Gandhi (2019); > Cyperus speciosus Vahl — S; > Torulinum confertum Desv. ex Ham. — Bah; Cyperus odoratus L. Basionym: Cyperus odoratus L. 1753

Links to other floras: = Cyperus odoratus - FNA23

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACW (taxonomic split from wetland indicator species)
• Eastern Mountains and Piedmont: FACW (taxonomic split from wetland indicator species)
• Great Plains: FACW (taxonomic split from wetland indicator species)
• Midwest: FACW (taxonomic split from wetland indicator species)
• Northcentral & Northeast: OBL (taxonomic split from wetland indicator species)

Heliophily ⓘ: 8