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pale flatsedge, yellow flatsedge

cyperus, flatsedge, galingale, nutsedge, umbrella-sedge

Habit Herbs, annual, cespitose. Herbs, perennial or less often annual, cespitose or not, rhizomatous, stoloniferous, rarely tuberous.
Culms

trigonous, (2–)4–30 cm × 0.4–2 mm, glabrous.

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

Leaves

1–5, (blades often absent, base of culm with 1 reddish sheath bearing minute blade tooth 1–2 mm), (3–)10–18 cm × (0.5–)1.5–2(–2.6) mm.

usually basal;

ligules absent;

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

Inflorescences

spikes 1–3, ovoid or ± digitate, 10–30 × 8–26 mm;

rays 1–4(–6), 0.5–3(–9) cm;

bracts 2–3, approximately horizontal, 1–12 cm × 0.5–2.5 mm.

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

1–6, compressed, oblong-lanceoloid, 5–15 × (2–)2.3–2.8 mm;

floral scales (4–)8–24, closely imbricate, laterally yellow to yellowish brown, margins light brown to clear, medially green, laterally ribless, medially 2–3-ribbed, 2-keeled basally, ovate, (1.5–)1.8–2.2 × 1.8 mm, apex obtuse.

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

Flowers

stamens 3;

anthers 0.4 mm, connectives not prolonged;

styles 0.5–1 mm;

stigmas 0.5–0.8 mm.

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

jet black to reddish brown, slightly stipitate, obovoid, 1–1.2 × 0.8 mm, apex apiculate, surface with network of rectangular longitudinally elongate cells and transverse undulations.

biconvex, flattened, or trigonous.

Cyperus flavescens

Cyperus

Phenology Fruiting summer–early fall.
Habitat Damp, often disturbed soils
Elevation 0–800 m (0–2600 ft)
Distribution
from FNA
AL; AR; CA; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV; ON; South America; West Indies; Eurasia; Africa
[WildflowerSearch map]
[BONAP county map]
from USDA
Pantemperate and tropical
[BONAP county map]
Discussion

North American populations have been distinguished as Cyperus flavescens var. poiformis; their taxonomic separation was not supported by M. L. Corcoran’s (1941) careful study. Plants of Mexico and Central America consistently have purplish rather than yellowish floral scales and may be recognized as C. flavescens var. piceus (Liebmann) Fernald (G. C. Tucker 1983, 1994).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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. 162. FNA vol. 23, p. 141. Authors: Gordon C. Tucker*, Brian G. Marcks*, J. Richard Carter *.
Parent taxa Cyperaceae > Cyperus > subg. Pycreus Cyperaceae
Sibling taxa
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, C. bipartitus, C. cephalanthus, C. compressus, C. croceus, C. cuspidatus, C. dentatus, C. dentoniae, C. diandrus, C. difformis, C. digitatus, C. dipsaceus, C. distans, C. distinctus, C. drummondii, C. echinatus, C. elegans, C. entrerianus, C. eragrostis, C. erythrorhizos, C. esculentus, C. fendlerianus, C. filicinus, C. filiculmis, C. filiformis, C. flavicomus, C. floribundus, C. fugax, C. fuligineus, C. fuscus, C. giganteus, C. gracilis, C. granitophilus, C. grayi, C. grayoides, C. haspan, C. hermaphroditus, C. houghtonii, C. hypopitys, C. hystricinus, C. involucratus, C. iria, C. laevigatus, C. lancastriensis, C. lanceolatus, C. lecontei, C. lentiginosus, C. ligularis, C. lupulinus, C. manimae, C. microiria, C. mutisii, C. niger, C. ochraceus, C. odoratus, C. onerosus, C. ovatus, C. owanii, C. oxylepis, C. pallidicolor, C. papyrus, C. parishii, C. pilosus, C. planifolius, C. plukenetii, C. polystachyos, C. prolifer, C. prolixus, C. pseudothyrsiflorus, C. pseudovegetus, C. pumilus, C. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, C. seslerioides, C. setigerus, C. spectabilis, C. sphacelatus, C. sphaerolepis, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus, C. virens
Subordinate taxa
C. subg. Cyperus, C. subg. Diclidium, C. subg. Juncellus, C. subg. Pycnostachys, C. subg. Pycreus
Synonyms C. flavescens var. poiformis, C. poiformis, Pycreus flavescens
Name authority Linnaeus: Sp. Pl. 1: 46. (1753) Linnaeus: Sp. Pl. 1: 44. (1753): Gen. Pl. ed. 5, 26. (1754)
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