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Asian flatsedge, smallflower umbrella sedge, variable flatsedge

Baldwin's flatsedge

Habit Herbs, annual, cespitose. Herbs perennial, cespitose.
Culms

1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous.

trigonous, (4–)14–45 cm × 1–2 mm, glabrous.

Leaves

2–7, flat, (2–)7–22 cm × 2.2–4 mm.

yellow-green, flat, 18–44 cm × 3–4.5 mm.

Inflorescences

heads dense, 7–17 mm diam.; when rays short, heads sessile or nearly so, then densely irregularly lobate, 12–35 mm diam.;

rays 1–5, 2–32 mm;

bracts 2–4, longest bract erect or nearly so, appearing as continuation of culm, other bracts horizontal to ascending, 1–22 cm × 0.5–3.5 mm, margins and keel minutely scabridulous.

spikes densely to loosely globose to ovoid, 10–20 mm wide;

rays (3–)5–9(–14), 1–15(–26) cm;

rachis 3–6(–9) mm;

bracts (4–)6–9(–11), horizontal to ascending at 45°, flat, 1–30 cm × 0.5–4 mm;

rachilla deciduous, wings persistent, 0.3–0.5(–0.8) mm wide.

Spikelets

30–120, greenish brown to purplish brown, oblong-ellipsoid, compressed, (2–)3–5(–6) × 0.8–1.2 mm;

floral scales (6–)12–20(–30), laterally clear margins, stramineous to deep purple, medially greenish, stramineous, or purplish, laterally ribless, medially 3-ribbed, obovate to orbiculate, 0.6–0.8 × 0.6–0.8 mm, apex mucronulate.

(10–)30–50, oblong to lanceoloid, quadrangular to subterete, compressed, 4–8 × 1–1.3 mm;

distal spikelet spreading or ascending;

floral scales persistent, (1–)2–4(–6), appressed, whitish with red speckles, laterally 2–4-ribbed, ovate, 2.3–3.6 × 1.8–2.2 mm.

Flowers

stamens 1 or 2;

anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged;

styles 0.1 mm;

stigmas 0.1–0.3 mm.

anthers 0.5 mm;

styles 0.6–1.3 mm;

stigmas 1.2–2.6 mm.

Achenes

light brown, obovoid-ellipsoid, 0.6–0.8 × 0.3–0.4 mm (as long as subtending scale), base cuneate, apex obtuse, apiculate, surfaces finely reticulate, papillose.

reddish brown to nearly black, sessile, oblong, ellipsoid, 2–2.4 × 0.4–0.5(–0.7) mm, apex ± truncate-emarginate, apiculate, surfaces puncticulate.

Cyperus difformis

Cyperus croceus

Phenology Fruiting summer. Fruiting summer–early fall.
Habitat Disturbed, muddy soils, shallow waters Disturbed, sunny areas, coastal rocks, moist thickets
Elevation 0–1000 m (0–3300 ft) 0–200 m (0–700 ft)
Distribution
from FNA
AL; AZ; CA; FL; GA; ID; KY; LA; MS; NC; NJ; NM; OR; PA; SC; TN; TX; VA; Mexico; South America; West Indies (Puerto Rico); Central America (Nicaragua, Panama); Eurasia; Indian Ocean Islands; Pacific Islands; Australia [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; DE; FL; GA; LA; MD; MO; MS; NC; NJ; OK; PA; SC; TN; TX; VA; WV; Mexico; Central America; West Indies; South America (Venezuela)
[WildflowerSearch map]
[BONAP county map]
Discussion

Cyperus difformis is naturalized in the New World and native to the Old World, where it ranges from southern Europe to southern Africa and eastward to Southeast Asia and Australia.

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

Cyperus globulosus Aublet is a synonym of C. luzulae (Linnaeus) Rottbøll ex Retzius, which is a widespread neotropical species, and it has long been misapplied to Cyperus croceus (G. C. Tucker 1987).

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

Source FNA vol. 23, p. 156. FNA vol. 23, p. 183.
Parent taxa Cyperaceae > Cyperus > subg. Pycnostachys 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. 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. 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. 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. 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
Synonyms C. lateriflorus C. baldwinii, C. cyclostachyus, C. echinatus var. multiflora, C. globulosus var. pseudofiliculmis, C. globulosus var. robustus, C. plankii, C. retrorsus var. robustus, Mariscus bracheilema, Mariscus brittonii
Name authority Linnaeus: Cent. Pl. II, 6. (1756) Vahl: Enum. Pl. 2: 357. (1805)
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