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pale flatsedge, yellow flatsedge

fuzzy flatsedge

Habit Herbs, annual, cespitose. Herbs, annual or perennial, cespitose; stolons slender, to 5 cm × 1.5 mm.
Culms

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

trigonous, 25–90 cm × 2 mm, hispidulous or glabrous on angles distally.

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.

flat, 10–35 cm × 3–10 mm.

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.

spikes 1–4(–6), loosely oblong-ovoid, 2–3 × 1–2 cm;

rays 3–10, 1–16 cm; 2d order rays to 3 cm;

rachis hispidulous, prickles slender, 0.1–0.2 mm;

bracts 3–5, ± ascending, flat, 5–35 cm × 0.5–5(–7) mm;

rachilla persistent, wingless.

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.

15–40, linear-lanceoloid, compressed, 6–12 × 1.5–2 mm;

floral scales deciduous, 8–16, light brown with clear border, laterally 2–3-ribbed, ovate, 1.8–2 × 1.2–1.6 mm;

apex entire, emarginate, or mucronulate, mucro at most 0.3 mm.

Flowers

stamens 3;

anthers 0.4 mm, connectives not prolonged;

styles 0.5–1 mm;

stigmas 0.5–0.8 mm.

anthers 0.4 mm;

styles 0.6 mm;

stigmas 1 mm.

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.

brown, sessile, broadly ellipsoid, 1–1.2 × 0.5 mm, apex obtuse, apiculate, surfaces puncticulate.

Cyperus flavescens

Cyperus pilosus

Phenology Fruiting summer–early fall. Fruiting summer.
Habitat Damp, often disturbed soils Rice fields, wetlands, emergent muddy shores
Elevation 0–800 m (0–2600 ft) 0–50 m (0–200 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
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from FNA
FL; LA; MS; SC; Asia [Introduced in North America]
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[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.)

Cyperus pilosus was naturalized in the flora from eastern Asia, apparently early in the twentieth century.

The combination of hispidulous rachis and loosely oblong-ovoid spikes is sufficient to distinguish Cyperus pilosus from any others with deciduous floral scales.

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

Source FNA vol. 23, p. 162. FNA vol. 23, p. 166.
Parent taxa Cyperaceae > Cyperus > subg. Pycreus Cyperaceae > Cyperus > subg. Cyperus
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
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. flavescens, 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. 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
Synonyms C. flavescens var. poiformis, C. poiformis, Pycreus flavescens
Name authority Linnaeus: Sp. Pl. 1: 46. (1753) Vahl: Enum. Pl. 2: 354. (1805)
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