OregonFlora: Cyperus reflexus vs. Cyperus schweinitzii

	Cyperus reflexus	Cyperus schweinitzii
		Schweinitz's flatsedge
Habit		Plants perennial, rhizomatous.
Culms		trigonous; (10)20–50 cm × (0.6)1–2 mm.
Leaves		(2)20–35 cm × 2–6 mm; proximal leaves bladeless.
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).
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.
Flowers		anthers 0.8–1.4 mm; styles 0.1–0.3 mm; stigmas 1.5–3 mm.
Achenes		broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm; base cuneate to more or less stipe-like.
2n		=166.

	Cyperus reflexus	Cyperus schweinitzii
Distribution	[BONAP county map]	[WildflowerSearch map] [BONAP county map]
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.
Source		Flora of Oregon, volume 1, page 236 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	C. acuminatus, C. aggregatus, C. bipartitus, C. difformis, C. eragrostis, C. erythrorhizos, C. esculentus, C. fuscus, C. niger, C. odoratus, C. schweinitzii, C. squarrosus, C. strigosus	C. acuminatus, C. aggregatus, C. bipartitus, C. difformis, C. eragrostis, C. erythrorhizos, C. esculentus, C. fuscus, C. niger, C. odoratus, C. squarrosus, C. strigosus
Synonyms		Cyperus x mesochorus, Cyperus bushii, Cyperus lupulinus, Cyperus lupulinus ssp. lupulinus, Cyperus lupulinus ssp. macilentus
Web links	Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Cyperus reflexus

Cyperus schweinitzii

Schweinitz's flatsedge

Habit

Plants perennial, rhizomatous.

Culms

trigonous; (10)20–50 cm × (0.6)1–2 mm.

Leaves

(2)20–35 cm × 2–6 mm;

proximal leaves bladeless.

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).

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.

Flowers

anthers 0.8–1.4 mm;

styles 0.1–0.3 mm;

stigmas 1.5–3 mm.

Achenes

broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm;

base cuneate to more or less stipe-like.

=166.

Cyperus reflexus

Cyperus schweinitzii

Distribution

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

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.