Cyperus rotundus

Linnaeus

Sp. Pl. 1: 45. 1753.

Common names: Purple nut-sedge coco-grass
Illustrated
Treatment appears in FNA Volume 23. Treatment on page 169. Mentioned on page 146, 168, 170.

Herbs, perennial, stoloniferous; stolons (2–) 5–12 cm × 1–2 mm, bearing tubers 3–8 (–12) mm diam., wiry, springy when dried, indurate. Culms trigonous, 10–35 (–40) cm × 0.7–3.4 mm, basally indurate, glabrous. Leaves V-shaped to flanged V-shaped, 5–30 cm × 2–6 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. 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. Flowers: anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–) 2–3.3 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.


Phenology: Fruiting summer–fall.
Habitat: Croplands, disturbed soils usually
Elevation: 0–400 m

Distribution

V23 277-distribution-map.jpg

Ala., Ariz., Ark., Calif., Fla., Ga., La., Miss., Mo., N.Mex., N.C., S.C., Tenn., Tex., Va., Mexico, Central America, South America, Asia, Africa, Australia

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.

Selected References

None.

Lower Taxa

None.

"shortened" is not a number.

... more about "Cyperus rotundus"
ellipsoid +
0.17 cm1.7 mm <br />0.0017 m <br /> (0.19 cm1.9 mm <br />0.0019 m <br />) +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
0.8mm +  and 1mm +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
obtuse;obtuse +
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
Linnaeus +
persistent +  and deciduous +
decurrent +
w--shaped +  and keeled +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
0.5 cm5 mm <br />0.005 m <br /> (10 cm100 mm <br />0.1 m <br />) +
horizontal +  and ascending +
v--shaped +, v-shaped +  and flanged +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
parallel +  and divergent +
terete +, rolled +  and plicate +
Purple nut-sedge +  and coco-grass +
35 cm350 mm <br />0.35 m <br /> (40 cm400 mm <br />0.4 m <br />) +
10 cm100 mm <br />0.1 m <br /> (35 cm350 mm <br />0.35 m <br />) +
scabridulous +
trigonous +
indurate +
0.7mm;3.4mm +
Ala. +, Ariz. +, Ark. +, Calif. +, Fla. +, Ga. +, La. +, Miss. +, Mo. +, N.Mex. +, N.C. +, S.C. +, Tenn. +, Tex. +, Va. +, Mexico +, Central America +, South America +, Asia +, Africa +  and Australia +
0–400 m +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.26 cm2.6 mm <br />0.0026 m <br />) +
purple +  and reddish-brown +
0.26 cm2.6 mm <br />0.0026 m <br /> (0.34 cm3.4 mm <br />0.0034 m <br />) +
appressed +  and spreading +
0.22 cm2.2 mm <br />0.0022 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
hypogynous +  and subtending +
biconvex +  and trigonous +
Croplands, disturbed soils usually +
subumbellate +  and capitate +
spreading +  and erect +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
5 cm50 mm <br />0.05 m <br /> (?) +  and 30 cm300 mm <br />0.3 m <br /> (?) +
v--shaped +, v-shaped +  and flanged +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
with (1-)3-6(-30) bristles and/or scales +
Fruiting summer–fall. +
2-3(-4)-carpellate +
antrorse +  and extrorse +
3 (?) +  and 1 (?) +
continuous +, articulate +, winged +  and wingless +
conspicuous +
unequal +
4 +  and 6 +
0.2 cm2 mm <br />0.002 m <br /> (10 cm100 mm <br />0.1 m <br />) +
adventitious +
basal +  and proximal +
cylindric;compressed +
cylindric +
W2 +, W1 +  and Illustrated +
2.5 cm25 mm <br />0.025 m <br /> (3 cm30 mm <br />0.03 m <br />) +
3 cm30 mm <br />0.03 m <br /> (5 cm50 mm <br />0.05 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
ellipsoid +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (4 cm40 mm <br />0.04 m <br />) +
compressed +
1.3mm;1.8mm +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
papillate +
0.2 cm2 mm <br />0.002 m <br /> (0.33 cm3.3 mm <br />0.0033 m <br />) +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
indurate +  and springy +
1mm +  and 2mm +
2-3-fid +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
Undefined subg. Chlorocyperus +, Cyperus subg. Mariscus +  and Undefined subg. Papyrus +
Cyperus rotundus +
Cyperus subg. Cyperus +
species +
0.5mm +  and 1mm +