Cyperus cephalanthus

Torrey & Hooker

Ann. Lyceum Nat. Hist. New York. 3: 431. 1836.

Illustrated
Synonyms: Cyperus laetus var. cephalanthus (Torrey & Hooker) Kükenthal
Treatment appears in FNA Volume 23. Mentioned on page 180.

Herbs, perennial, rhizomatous. Culms trigonous, 40–70 (–100) cm × 2–3 mm, scabrid or hirtellate, either immediately proximal to apex or over distal 1/2 of culm. Leaves flat, 30–80 cm × 4–10 mm, scabrid on margins, ribs on abaxial surface. Inflorescences: spikes ovoid, 12–20 × 13–18 mm; rays 3–6, 4–10 (–16) cm, glabrous; bracts 3–5, ± horizontal to reflexed, 3–12 (–36) cm × 0.4–3 (–5) mm, scabrid like leaves; rachilla deciduous, essentially wingless or wings inconspicuous, hyaline, 0.1 (–0.2) mm wide. Spikelets 25–50 (–80), oblong, quadrangular-compressed, 5–10 × 2.5–3.5 mm; floral scales deciduous, 4–10 (–14), marginally clear, laterally brownish to clear distally, or light-brown or reddish-brown, blunt, laterally 3 (–4) -ribbed, ovatelanceolate, 2.5–3 × (1.2–) 1.4–2 mm, often erose apically, apex acute to obtuse, entire or emarginate. Flowers: anthers 0.4–0.6 mm; styles 0.8–1.2 mm; stigmas 2 mm. Achenes brown to reddish-brown, ± stipitate, ellipsoid, 1.2 × 0.5–0.6 mm, apex obtuse, scarcely to distinctly apiculate, surfaces puncticulate.


Phenology: Fruiting summer.
Habitat: Wet prairies
Elevation: 0–50 m

Distribution

V23 306-distribution-map.jpg

La., Okla., Tex., South America (Argentina), South America (Brazil), South America (Paraguay), South America (Uruguay)

Discussion

The combination of spreading floral scales and scabrid culms separates this rather uncommon species from any others occurring in its range. The scarcity of Cyperus cephalanthus in the United States and its disjunct distribution suggest it might be naturalized rather than native. It was collected early in the nineteenth century in Louisiana, and the amphitropical distribution is not without parallel in the genus (cf. 12. C. eragrostis).

Cyperus cephalanthus has been treated as a variety of the widespread, polymorphic South American C. laetus (G. Kükenthal 1935–1936). Recognition of C. cephalanthus as a species follows recent American floristic practice.

Selected References

None.

Lower Taxa

None.
... more about "Cyperus cephalanthus"
brown +  and reddish-brown +
1.2 cm12 mm <br />0.012 m <br /> (?) +
ellipsoid +
0.5mm;0.6mm +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
emarginate +  and entire +
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
Torrey & Hooker +
shortened +
persistent +  and deciduous +
decurrent +
w--shaped +  and keeled +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
12 cm120 mm <br />0.12 m <br /> (36 cm360 mm <br />0.36 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
3 cm30 mm <br />0.03 m <br /> (12 cm120 mm <br />0.12 m <br />) +
less horizontal +  and reflexed +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
parallel +  and divergent +
terete +, rolled +  and plicate +
70 cm700 mm <br />0.7 m <br /> (100 cm1,000 mm <br />1 m <br />) +
40 cm400 mm <br />0.4 m <br /> (70 cm700 mm <br />0.7 m <br />) +
hirtellate +  and scabrid +
scabridulous +
trigonous +
2mm;3mm +
La. +, Okla. +, Tex. +, South America (Argentina) +, South America (Brazil) +, South America (Paraguay) +  and South America (Uruguay) +
0–50 m +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
laterally brownish +  and clear distally +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
ovatelanceolate +  and blunt +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
hypogynous +  and subtending +
biconvex +  and trigonous +
Wet prairies +
subumbellate +  and capitate +
spreading +  and erect +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
30cm +  and 80cm +
0.4 cm4 mm <br />0.004 m <br /> (1 cm10 mm <br />0.01 m <br />) +
with (1-)3-6(-30) bristles and/or scales +
Fruiting summer. +
2-3(-4)-carpellate +
antrorse +  and extrorse +
3 (?) +  and 1 (?) +
Ann. Lyceum Nat. Hist. New York. +
conspicuous +
10 cm100 mm <br />0.1 m <br /> (16 cm160 mm <br />0.16 m <br />) +
unequal +
3 +  and 6 +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
adventitious +
basal +  and proximal +
cylindric;compressed +
cylindric +
Illustrated +
1.2 cm12 mm <br />0.012 m <br /> (2 cm20 mm <br />0.02 m <br />) +
1.3 cm13 mm <br />0.013 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
25 +  and 50 +
quadrangular-compressed;oblong +
2.5mm;3.5mm +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
2 cm20 mm <br />0.02 m <br /> (?) +
2-3-fid +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
Cyperus laetus var. cephalanthus +
Cyperus cephalanthus +
Cyperus subg. Cyperus +
species +
inconspicuous +
0.1 +, 0.1mm +  and 0.2mm +