Cyperus grayoides |
Cyperus pseudothyrsiflorus |
|
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Illinois flatsedge, Mohlenbrock's sedge, umbrella sedge |
flatsedge |
|
Habit | Herbs, perennial, cespitose, rhizomatous, tuberlike. | Herbs, perennial, cespitose, rhizomatous. |
Culms | trigonous, 5–35 cm × 0.7–1.2 mm, glabrous. |
trigonous, base thickened, tuberous, 15–40 cm × 2–2.6 mm, glabrous. |
Leaves | V-shaped, 5–25 cm × 1.5–3.5 mm, slightly scabridulous on abaxial margins, midrib. |
flat to V-shaped, 10–30 cm × (3–)4–5.8 mm. |
Inflorescences | spikes loosely ± globose, 15–25 mm wide; rays 1–10 cm; rachis 1–4 mm; bracts 3–7, ascending, V-shaped, 3–20 cm × 1–3 mm; rachilla deciduous, wingless. |
spike 1, densely oblong to ellipsoid, 10–20 × 10–20 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 persistent, 0.5–0.7 mm wide. |
Spikelets | 3–24, compressed, oblong-lanceoloid, 4–12 × 2.5–3.2 mm; floral scales deciduous, 3–9, pale reddish brown, ovate, laterally 3–5-ribbed, 2.5–3 × 2–2.4 mm, apex acute to obtuse. |
(5–)10–20(–30), linear to oblong, quadrangular, (2.2–)4–12(–16) × 0.7–1.2 mm, densly packed on rachis with 11–21 spikelets per 5 mm rachis; distal spikelet spreading or ascending; floral scales persistent, 1–5, appressed, laterally whitish to reddish brown, medially green, narrowly oblong to ovate, laterally 3–6-ribbed, 2.4–3.4 × 1.6–2 mm, apex rounded to ± acute, entire, mucronate, mucro 0.1–0.3 mm; sterile terminal scale, involute, only 0.4–0.6 mm wide with mucro 0.2–0.5 mm. |
Flowers | anthers 1–1.2 mm; styles 0.4–0.6 mm; stigmas 1–2 mm. |
anthers (0.3–)0.4–0.7 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
Achenes | dark brown, ± stipitate, ellipsoid, 2–2.4 × 0.9–1.2 mm, apex obtuse, apiculate, surfaces glabrous, puncticulate, or papillose. |
light brown, sessile to slightly stipitate, ellipsoid to narrowly ellipsoid to narrowly obovoid, 1.4–1.9 × 0.5–0.75 mm, apex slightly apiculate, surfaces puncticulate. |
2n | = 166. |
|
Cyperus grayoides |
Cyperus pseudothyrsiflorus |
|
Phenology | Fruiting summer. | Fruiting mid summer–early fall (Jul–Sep). |
Habitat | Sand prairies, waste places, fallow fields | Damp, disturbed soils, croplands |
Elevation | 100–300 m (300–1000 ft) | 0–1000 m (0–3300 ft) |
Distribution |
AR; IL; LA; MO; TX
|
TX; Mexico |
Discussion | Of conservation concern. Cyperus grayoides is in the Center for Plant Conservation’s National Collection of Endangered Plant’s. See frontispiece. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 23. | FNA vol. 23. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. uniflorus var. pseudothyrsiflorus | |
Name authority | Mohlenbrock: Brittonia 11: 255, fig. 1. (1959) | (Kükenthal) J. Rich. Carter & S. D. Jones: Rhodora 99: 330. (1998) |
Web links |