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foothill flatsedge

Rio Grande sedge

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

1–10(–25), roundly trigonous, 3–12 cm × 0.3–0.8 mm, glabrous.

trigonous, basally tuberous thickened, 15–40 cm × 1–2.5 mm, glabrous.

Leaves

1–3–(4), 1–6 cm × 1(–1.5) mm.

flat to V-shaped, 10–30 cm × 1–2 mm.

Inflorescences

if rays absent heads single, dense, sessile, digitate, 5–20 × 10–30 mm, single heads 10–30(–50) mm;

rays usually absent, if present 1–8 cm; 2d order rays infrequently present, 1–2 cm;

bracts 3–6, erect to oblique, flat to V-shaped,(0.5–)2–10(–15) cm × 0.5–2 mm.

spike 1, densely oblong to ellipsoid, 8–36 × 8–20 mm;

rays 4–12, 10–20 cm;

bracts 3–6, horizontal to ascending at 30°, V-shaped, 3–15 cm × (3–)4–5.8 mm;

rachilla deciduous, wings 0.5–0.7 mm wide.

Spikelets

5–10(–20), linear to linear-lanceoloid, (5–)8–12(–35) × 1.6–2.3(–2.5) mm;

floral scales (6–)16–30(–76), laterally glossy reddish brown to brown, medially greenish, sometimes also reddish or brownish, laterally ribless, medially strongly 3-ribbed, ovate-lanceolate, 1.9–2(–2.3) mm (including prominent excurved cusp of 0.3–0.5 mm) × 0.8–1.1 mm, apex truncate, emarginate, or cuspidate.

(5–)20–35(–60), linear to oblong, quadrangular; 4–12(–21) × 0.7–1.2 mm, base narrowed to 0.4–1 mm;

floral scales persistent, 1–3(–5), appressed, laterally whitish to reddish brown, stramineous with reddish spots, medially green, laterally 3–6-ribbed (midrib distinctly scabrid at 30X), narrowly oblong to ovate, 2.6–4.8 × 1.6–2 mm;

apex rounded to ± acute, entire, with mucro 0.3–0.5 mm;

sterile terminal scale involute, 0.4–0.6 mm wide, uncinate;

distal floral scales with cusp 0.6–1.9.

Flowers

stamens (1–)2–3;

anthers ellipsoid, 0.3 mm, connectives not prolonged;

styles 0.3–0.4 mm;

stigmas 0.4–0.7 mm.

anthers 0.5–1.3 mm;

styles 0.4–0.5 mm;

stigmas 0.5–0.9 mm.

Achenes

brown, slightly stipitate, obovoid to oblong, 0.8–0.9 × 0.4–0.5 mm, apex abruptly apiculate, surfaces papillose.

light brown to reddish brown, sessile to slightly stipitate, narrowly ellipsoid, 1.8–2.4 × 0.6–0.8 mm, apex slightly apiculate, surfaces puncticulate.

Cyperus amabilis

Cyperus floribundus

Phenology Fruiting summer. Fruiting mid summer–early fall (Jul–Sep).
Habitat Seasonally wet, sandy soils Damp, disturbed soils, croplands
Elevation 500 m (1600 ft) 0–1000 m (0–3300 ft)
Distribution
from FNA
AZ; Mexico; Central America; South America; Asia; Africa
[BONAP county map]
from FNA
TX; Mexico
[BONAP county map]
Discussion

Included previously in Cyperus retroflexus (or its synonym C. uniflorus), C. floribundus has a much narrower geographic range (southern Texas and northeastern Mexico) and differs in features of spikelet morphology (J. R. Carter and S. D. Jones 1997).

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

Source FNA vol. 23, p. 158. FNA vol. 23.
Parent taxa Cyperaceae > Cyperus > subg. Pycnostachys Cyperaceae > Cyperus > subg. Cyperus
Sibling taxa
C. acuminatus, C. aggregatus, C. alopecuroides, 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
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. 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. amabilis var. macrostachyus, C. aurantiacus, C. aureus, C. aureus var. aurantiacus, C. aureus var. macrostachyus, C. aureus var. oligostachyus, C. microstachyus, C. oligostachyus C. uniflorus var. floribundus, C. uniflorus
Name authority Vahl: Enum. Pl. 2: 318. (1805) (Kükenthal) J. Rich. Carter & S. D. Jones: Rhodora 99: 330. (1998)
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