Cyperus hermaphroditus |
Cyperus schweinitzii |
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Schweinitz's flatsedge |
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Habit | Plants perennial, rhizomatous. | |
Culms | trigonous; (10)20–50 cm × (0.6)1–2 mm. |
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Leaves | (2)20–35 cm × 2–6 mm; proximal leaves bladeless. |
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Inflorescences | clusters head-like to cylindric, 10–25 × 7–16 mm; rays 3–5, 1.5–8(15) cm; inflorescence bracts erect (or declined at most 25–30° from vertical). |
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Spikes | (1)5–10(20), oblong to linear-oblong, quadrangular in cross section, 7–10(18) × (2.8)3.2–4(4.5) mm; rachilla more or less deciduous; wingless; floral scales deciduous; (1)5–10(14), spreading, broadly ovate to oblong-ovate; (2.3)2.8–3.2 × (2)2.4–3.2 mm, stramineous or dull whitish, sometimes also red-spotted, with green mid-stripe; lateral ribs 2–3; medial ribs 3; apex broadly rounded, often clear-erose; cusp 0.1–0.4 mm in proximal scales, 0.3–1 mm in distal scales. |
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Flowers | anthers 0.8–1.4 mm; styles 0.1–0.3 mm; stigmas 1.5–3 mm. |
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Achenes | broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm; base cuneate to more or less stipe-like. |
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2n | =166. |
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Cyperus hermaphroditus |
Cyperus schweinitzii |
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Distribution | ||
Discussion | Sand bars in rivers, sandy lake shores, and sandy disturbed meadows. 200–400 m. BW. WA; east to MA, south to AZ, TX, Mexico. Exotic. The first Oregon specimens of this species were collected in 1994 along the Snake River and the lower reaches of its major tributaries. These specimens have been variously identified as C. schweinitzii, C. lupulinus ssp. lupulinus, and their hybrid C. × mesochorus. Cyperus lupulinus differs from C. schweinitzii in having more (15–60) spikes per inflorescence, forming a denser, nearly globose cluster that forces the inflorescence bracts to spread widely or reflex. Its anthers are 0.3–0.6 mm long, its styles are about 1 mm long, and its stigmas are about 1–1.5 mm long. The hybrids differ from C. lupulinus in having obconic spikes and ascending leafy bracts. They differ from C. schweinitzii in having smoother, not scabrous culms, a denser cluster of spikes, and spikes that are more flattened along the keels. |
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Source | Flora of Oregon, volume 1, page 236 Barbara Wilson, Richard Brainerd, Nick Otting |
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Sibling taxa | ||
Synonyms | Cyperus x mesochorus, Cyperus bushii, Cyperus lupulinus, Cyperus lupulinus ssp. lupulinus, Cyperus lupulinus ssp. macilentus | |
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