Flora of North America species comparison

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Cyperus

cyperus, flatsedge, galingale, nutsedge, umbrella-sedge
Habit Herbs, perennial or less often annual, cespitose or not, rhizomatous, stoloniferous, rarely tuberous.
Culms

solitary or not, trigonous or round, glabrous or scabridulous with extrorse or antrorse (rarely retrorse) prickles.
Leaves

usually basal;

ligules absent;

blades keeled abaxially, flat, V-, or inversely W-shaped in cross section.
Inflorescences

terminal, rarely pseudolateral, 1st order subumbellate to capitate, 2d order with spicate or digitately arranged spikelets, rarely a solitary spikelet;

spikelets 1–150; 1st order rays unequal (rarely equal) in length, produced singly from the axils of inflorescence bracts;

involucral bracts 1–22, spirally arranged at culm apex, spreading to erect, leaflike.
Spikelets

scales to 76, distichous, each subtending flower, cylindric to compressed, borne spicately or digitately at ends of rays (occasionally proliferous).
Flowers

bisexual [rarely unisexual], in axils of distichous floral scales, bases often decurrent onto rachilla as ± hyaline wings;

perianth absent;

stamens 1–3;

styles linear, 2–3-fid, base deciduous or persistent;

stigmas 2–3.
Achenes

biconvex, flattened, or trigonous.

Cyperus
Distribution
from USDA
Pantemperate and tropical
[BONAP county map]
Discussion

Species ca. 600 (96 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Stigmas 2 (3 in C. serotinus); achenes biconvex.
→ 2
1. Stigmas 3; achenes trigonous, plano-convex, or terete.
→ 3
2. Achenes laterally flattened, borne with edge toward rachilla.
subg. Pycreus
2. Achenes dorsiventrally flattened, borne with face toward rachilla.
subg. Juncellus
3. Spikelets borne in digitate clusters (rarely singly) or in umbellate or glomerulate heads.
subg. Pycnostachys
3. Spikelets borne in spikes on conspicuous rachis.
→ 4
4. Rachilla continuous or articulate only at base.
subg. Cyperus
4. Rachilla articulate at base of each scale, mature spikelet disarticulating into segments consisting of scale, internode, and rachilla wings.
subg. Diclidium
Source FNA vol. 23, p. 141. Authors: Gordon C. Tucker*, Brian G. Marcks*, J. Richard Carter *.
Parent taxa Cyperaceae
Subordinate taxa
C. subg. Cyperus, C. subg. Diclidium, C. subg. Juncellus, C. subg. Pycnostachys, C. subg. Pycreus
Name authority Linnaeus: Sp. Pl. 1: 44. (1753): Gen. Pl. ed. 5, 26. (1754)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

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