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epiphytic flatsedge

buttonbush flatsedge

Habit Herbs, perennial, cespitose, rhizomatous. Herbs, perennial, rhizomatous.
Culms

trigonous, compressed, 15–75 cm × 0.5–3 mm, glabrous.

trigonous, 40–70(–100) cm × 2–3 mm, scabrid or hirtellate, either immediately proximal to apex or over distal 1/2 of culm.

Leaves

1–3, 5–30 cm × 1–2 mm.

flat, 30–80 cm × 4–10 mm, scabrid on margins, ribs on abaxial surface.

Inflorescences

spikes 1(–2), ovoid, 5–23 × 9–21 mm;

rays 2–3(–4), 0–15 mm;

if rays absent, head single, compact, sessile, (12–)15–20 mm diam.;

bracts 2–3, horizontal to vertical, 2–14 cm × 0.5–3.5 mm.

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

1–6, oblong-lanceoloid, 5–26 × 2–3 mm;

floral scales 12–54, closely imbricate, laterally yellowish brown, medially pale brown, occasionally greenish, laterally 1-ribbed, medially 3-ribbed, distinctly 2-keeled basally, ovate, 1.8–2.6 × 1.4–1.7 mm, apex obtuse.

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, ovate-lanceolate, 2.5–3 × (1.2–)1.4–2 mm, often erose apically, apex acute to obtuse, entire or emarginate.

Flowers

stamens 2;

anthers 0.4–0.5 mm, connectives not prolonged;

styles 0.3–1 mm;

stigmas 0.6–0.8(–1) mm.

anthers 0.4–0.6 mm;

styles 0.8–1.2 mm;

stigmas 2 mm.

Achenes

brown, network of ridges forming isodiametric or square cells, stipitate, obovoid to ellipsoid, 1.1–1.3 × (0.5–)0.6 mm, apex acute to broadly rounded, surfaces minutely punctate or finely papillose.

brown to reddish brown, ± stipitate, ellipsoid, 1.2 × 0.5–0.6 mm, apex obtuse, scarcely to distinctly apiculate, surfaces puncticulate.

Cyperus lanceolatus

Cyperus cephalanthus

Phenology Fruiting summer. Fruiting summer.
Habitat Marshes Wet prairies
Elevation 0–100 m (0–300 ft) 0–50 m (0–200 ft)
Distribution
from FNA
AL; FL; GA; LA; TX; Mexico; Central America; South America; Africa
[WildflowerSearch map]
[BONAP county map]
from FNA
LA; OK; TX; South America (Argentina, Brazil, Paraguay, Uruguay)
[BONAP county map]
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.

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

Source FNA vol. 23, p. 162. FNA vol. 23.
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. 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. 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. 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. densus, C. humboldtianus, C. lanceolatus var. compositus, Pycreus densus C. laetus var. cephalanthus
Name authority Poiret: in J. Lamarck et al., Encycl. 7: 245. (1806) Torrey & Hooker: Ann. Lyceum Nat. Hist. New York. 3: 431. (1836)
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