OregonFlora: Cyperus lanceolatus vs. Cyperus bipartitus

	Cyperus lanceolatus	Cyperus bipartitus
		shining flatsedge
Habit		Plants annual, densely cespitose, with fibrous roots.
Culms		roundly trigonous, 3–25(30) cm × 0.3–1.4 mm.
Leaves		1–8 cm × 1–2 mm.
Inflorescences		cluster head-like, 1, loosely ovoid, compressed, 7–14 × 9–14 mm; rays 1–4; to 2(3) cm; inflorescence bracts 2–3; horizontal to ascending at 45(75)°.
Spikes		3–5(8), flattened, oblong to oblong-lanceoloid, 8–18 × 2–2.6(3) mm; floral scales (6)10–26(32), closely overlapping, 1.9–2.7 × 1.8–2.3 mm, oblong to ovate; light to dark brown, with light brown mid-stripe; lateral ribs 0; medial ribs 2–3, 2-keeled; apex obtuse.
Flowers		anthers 0.4–0.5 mm; styles 0.6–1 mm; stigmas 1–1.5 mm.
Achenes		with network of ridges forming isodiametric or square cells, obovoid to ovoid, 1–1.3(1.5) × (0.6)0.8 mm.

	Cyperus lanceolatus	Cyperus bipartitus
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion		Shorelines exposed by seasonal low water levels, ditches, disturbed wetlands. 0–800 m. Col, CR, Sisk, WV. CA, ID, NV, WA; northeastern Canada, most of US, south to South America. Native. Cyperus bipartitus closely resembles C. niger, a taller rhizomatous perennial with clustered shoots that are often collected without the rhizomes.
Source		Flora of Oregon, volume 1, page 235 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. difformis, C. eragrostis, C. erythrorhizos, C. esculentus, C. fuscus, C. niger, C. odoratus, C. schweinitzii, C. squarrosus, C. strigosus
Synonyms		Cyperus niger var. rivularis, Cyperus rivularis
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: CA, OR, WA Local Web sites: CalFlora, CalPhotos, 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 lanceolatus

Cyperus bipartitus

shining flatsedge

Habit

Plants annual, densely cespitose, with fibrous roots.

Culms

roundly trigonous, 3–25(30) cm × 0.3–1.4 mm.

Leaves

1–8 cm × 1–2 mm.

Inflorescences

cluster head-like, 1, loosely ovoid, compressed, 7–14 × 9–14 mm;

rays 1–4; to 2(3) cm;

inflorescence bracts 2–3; horizontal to ascending at 45(75)°.

Spikes

3–5(8), flattened, oblong to oblong-lanceoloid, 8–18 × 2–2.6(3) mm; floral scales (6)10–26(32), closely overlapping, 1.9–2.7 × 1.8–2.3 mm, oblong to ovate; light to dark brown, with light brown mid-stripe;

lateral ribs 0; medial ribs 2–3, 2-keeled;

apex obtuse.

Flowers

anthers 0.4–0.5 mm;

styles 0.6–1 mm;

stigmas 1–1.5 mm.

Achenes

with network of ridges forming isodiametric or square cells, obovoid to ovoid, 1–1.3(1.5) × (0.6)0.8 mm.

Cyperus lanceolatus

Cyperus bipartitus

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Shorelines exposed by seasonal low water levels, ditches, disturbed wetlands. 0–800 m. Col, CR, Sisk, WV. CA, ID, NV, WA; northeastern Canada, most of US, south to South America. Native.

Cyperus bipartitus closely resembles C. niger, a taller rhizomatous perennial with clustered shoots that are often collected without the rhizomes.

Source

Flora of Oregon, volume 1, page 235
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa