Cyperus tetragonus |
Cyperus houghtonii |
|
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fourangle flatsedge |
Houghton's flatsedge |
|
Habit | Herbs, perennial, cespitose, rhizomatous. | Herbs, perennial, cespitose, bases cormose, rhizomatous. |
Culms | trigonous, (20–) 30–80 cm × 1–2.5 mm, glabrous or occasionally with scattered prickles on distal angles. |
trigonous, 5–50 cm × 0.5–1.5 mm, glabrous. |
Leaves | 9–11, flat to slightly V-shaped, 25–80 cm × 3.5–10 mm. |
V-shaped, 12–30 cm × 1–6 mm. |
Inflorescences | spikes (1–)3–6, loosely cylindric or oblong with parallel sides, 1.5–4 cm × 10–17 mm; rays 6–12, 2–25 cm, glabrous or rarely scabridulous proximal to spikes; bracts 6–11, ascending at 45°, flat, (1–)10–20(–26) cm × 1–10 mm; rachilla deciduous, wings persistent, 0.4–0.5 mm wide. |
spikes ± globose to broadly ovoid, 8–20 mm wide; rays 1–8 cm; rachis 2–5 mm, glabrous; bracts 3–8, weakly ascending, flat, 3–20 cm × 1–3.5 mm; rachilla deciduous, wingless. |
Spikelets | 10–60, narrowly ellipsoid, quadrangular, 5–8 × 1.5–2 mm; floral scales persistent, (2–)3–7, appressed, clear at maturity, laterally reddish to purplish brown, medially greenish, often erose at maturity, laterally 3–5-ribbed, medially 3-ribbed, ovate-elliptic, 2.5–3.2 × 1.8–2.1 mm, apex obtuse. |
3–18, compressed, ovoid to oblong-lanceoloid, 4–15 × 2.6–3.4 mm; floral scales deciduous, 3–18, laterally stramineous to reddish brown, laterally 3–4-ribbed, broadly ovate, 1.8–2.5 × 1.3–1.6 mm, apex with mucro 0.1–0.2 mm. |
Flowers | anthers 0.8–1 mm; styles 0.3–0.5 mm; stigmas 2–2.5 mm. |
anthers 0.5–0.7 mm; styles 0.4–0.6 mm; stigmas 1–1.5 mm. |
Achenes | brown to reddish brown, sessile, oblong-ovoid to broadly ellipsoid, slightly dorsiventrally flattened, 1.8–2 × 0.7–0.8 mm, apex obtuse, apiculate, surfaces papillose to puncticulate. |
dark brown, sessile, broadly ellipsoid, 1.5–2 × 1–1.5 mm, apex obtuse, apiculate, surface glabrous, puncticulate, or papillose. |
2n | = 168, 170, 172. |
|
Cyperus tetragonus |
Cyperus houghtonii |
|
Phenology | Fruiting summer–fall (Jun–Nov). | Fruiting summer. |
Habitat | Open woods, thickets, barrier islands | Riverbanks, sand bars, lakeshores, sand dunes, sandy openings in woods, especially among Jack pines |
Elevation | 0–1000 m (0–3300 ft) | 0–1100 m (0–3600 ft) |
Distribution |
AL; AZ; FL; GA; MS; NC; NM
|
IL; IN; MA; MD; ME; MI; MN; NH; NJ; NY; OH; PA; VA; VT; WI; WV; MB; ON; QC
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Discussion | The status of Cyperus pringlei from the southwestern United States requires further study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 23, p. 189. | FNA vol. 23, p. 175. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. pringlei, C. tetragonus var. pringlei, Mariscus tetragonus | |
Name authority | Elliott: Sketch Bot. S. Carolina 1: 71. (1821) | Torrey: Ann. Lyceum Nat. Hist. New York 3: 277. (1836) |
Web links |