Flora of North America species comparison

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Cyperus rotundus

Cyperus acuminatus

chaguan humatag, coco-grass, nutgrass, pakopako, purple nut-sedge

pale umbrella-sedge, sharp-point flatsedge, short flatsedge, short point cyperus, taper-tip cyperus, taper-tip flat sedge
Habit Herbs, perennial, stoloniferous; stolons (2–)5–12 cm × 1–2 mm, bearing tubers 3–8(–12) mm diam., wiry, springy when dried, indurate. Herbs, annual, cespitose.
Culms

trigonous, 10–35(–40) cm × 0.7–3.4 mm, basally indurate, glabrous.

roundly trigonous, (10–)20–30(–45) cm × 0.4–1.2 mm, distal 1/2 glabrous or infrequently scabridulous.
Leaves

V-shaped to flanged V-shaped, 5–30 cm × 2–6 mm.

2–6(–8), V-shaped or flat, 8–12(–16) cm × 1–2(–4) mm.
Inflorescences

spikes 1(–3), broadly ellipsoid, (12–)15–25(–30) × (12–)20–30(–50) mm, rays (3–)4–6(–7), 0.2–10 cm;, bracts (2–)3–5, horizontal to ascending at 45°, V-shaped to flanged V-shaped, 0.5–10 cm × 0.5–4 mm, rachilla persistent, wings 0.5–1 mm wide.

heads hemispheric, 7–12(–15) mm diam.;

rays 1–3(–5), 0.5–2 cm;

bracts 3–6, longest erect to ascending, flat to V-shaped, (1.5–)3–12(–25) cm × 1–2.5(–3.5) mm.
Spikelets

(2–)3–7(–12), compressed, linear, 4–40 × 1.3–1.8 mm, floral scales persistent, 6–36(–42), spreading or appressed, purple to reddish brown, with narrow clear border and green midrib, 7–9-ribbed, ovate, (1.8–)2.6–3.4 × 2.2–3 mm, apex obtuse.

(15–)25–50(–75), ovoid, compressed, 4–7 × 2–3 mm;

floral scales 8–20(–35), laterally yellowish, yellowish green, or light reddish brown, medially light brown or greenish brown, 2-keeled, subtly 1-ribbed, ovate-lanceolate, 1–2 × 1–1.4 mm, apex acute, mucronate, straight to excurved, glabrous or sparsely scabridulous.
Flowers

anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–)2–3.3 mm.

stamen 1;

anthers 0.5 mm;

styles 0.8–1.1 mm;

stigmas 0.5 mm.
Achenes

black, sessile, ellipsoid, abaxial face convex, adaxial face concave, 1.4–1.7(–1.9) × 0.8–1 mm, apex obtuse, surfaces puncticulate.

brown, stipitate, broadly ellipsoid, abruptly contracted to base, 0.8–1.1 × 0.3–0.4 mm, stipe 0.1 mm, apex acute, tapering to slender beak formed of persistent style base, surfaces papillose.

Cyperus rotundus

Cyperus acuminatus
Phenology Fruiting summer–fall. Fruiting summer–fall (Jul–Oct).
Habitat Croplands, disturbed soils usually Wet, often sandy shores and damp, disturbed soils
Elevation 0–400 m (0–1300 ft) 0–1500 m (0–4900 ft)
Distribution
from FNA
AL; AR; AZ; CA; FL; GA; LA; MO; MS; NC; NM; SC; TN; TX; VA; Mexico; Central America; South America; Asia; Africa; Australia
[WildflowerSearch map]
[BONAP county map]
from USDA
Mexico (Coahuila, Tamaulipas) [Ala., Ariz., Ark., Calif., Colo., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Mo., Mont., Nebr., N.H., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa. (introduced?), S.Dak., Tenn., Tex., Utah, Va., Wash., Wyo.]
[WildflowerSearch map]
[BONAP county map]
Discussion

Cyperus rotundus is documented in Connecticut, Delaware, New York, and Pennsylvania; there is no evidence of persistent populations.

Cyperus esculentus and C. rotundus are the only two species of subg. Cyperus in the New World that produce tuberiferous stolons. The two species also have persistent floral scales and persistent rachillas, a combination of characteristics not found in any other New World species of Cyperus.

Cyperus rotundus is distinguished from other species of the genus in the New World by its open spikes composed of linear reddish spikelets borne on a conspicuous slender rachis. Cyperus rotundus is usually acknowledged to be the world’s worst weed (cf. G. C. Tucker 1987). In the United States, it does not grow north of the mean 1°C January isotherm. Cyperus esculentus (preceding species) is a serious weed in much of the world, especially in cooler regions where the more tropical C. rotundus does not grow. Cyperus esculentus is able to tolerate lower air temperatures (as low as -18°C). The two species apparently differ also in their thermal optima for growth.

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

Cyperus acuminatus may be introduced in New Hampshire and New York.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 23, p. 169. FNA vol. 23, p. 152.
Parent taxa Cyperaceae > Cyperus > subg. Cyperus Cyperaceae > Cyperus > subg. Pycnostachys
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. 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. 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. 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. 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. acuminatus var. cyrtolepis, C. cyrtolepis, C. cyrtolepis var. denticarinatus, C. rufescens var. denticarinatus
Name authority Linnaeus: Sp. Pl. 1: 45. (1753) Torrey & Hooker: Ann. Lyceum Nat. Hist. New York 3: 435. (1836)
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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