Eleocharis microcarpa |
Eleocharis rostellata |
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small-fruit spikesedge, smallfruit spikerush |
beak spike-rush, beak spikesedge, walking sedge, walking spikerush |
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Habit | Plants usually annual, tufted, sometimes mat-forming via proliferating and arching inflorescences (stoloniferous), sometimes entirely vegetative; rhizomes absent. | Plants densely tufted, mat-forming by means of rooting culm tips. | ||||
Culms | often ascending or arching, quadrangular or broadly elliptic, 2–40 cm × 0.1–0.4(–0.6) mm, soft. |
1.5–3 times as wide as thick, 20–100 cm × 0.35–2 mm, firm to hard, wiry, with to 8 subacute ribs, rarely nearly smooth; some culms arching or decumbent and rooting at tips. |
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Leaves | distal leaf sheaths persistent or disintegrating, pale brown, green or red-brown, streaked or mottled red-brown or purple, translucent, membranous, apex narrowly acute. |
distal leaf sheaths not splitting abaxially, proximally dark red to brown, apex usually reddish. |
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Spikelets | basal spikelets absent; often proliferous, ovoid to ellipsoid or lanceoloid, terete, 2–10.7 × 1–2 mm, apex acute; proximal scale empty, persistent, amplexicaulous, dissimilar to floral scales, often longer, often resembling an involucral bract, ovate to lanceolate, midrib markedly thickened and broad and often prolonged beyond lamina; subproximal scale with flower; floral scales spiraled, colorless, whitish, or pale brown, streaked or mottled red-brown or purple, midribs green and red-brown or green and purple, ovate to elliptic, 0.8–1.5 × 0.4–0.8 mm, membranous, midrib obscure to prominent. |
ovoid, 5–17 × 2.5–5 mm, apex acute; spikelets on stolons rudimentary, non-flowering, proliferous when rooting; proximal scale empty, amplexicaulous, ovate, 2–4 mm; subproximal scale with flower; floral scales 20–40, 2–3 per mm of rachilla, stramineous to medium brown, midrib region paler, ovate, 3.5–6 × 2–3 mm, membranous to cartilaginous, apex entire, rounded to subacute. |
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Flowers | perianth bristles present or sometimes apparently absent; stamens 3; anthers 0.15–0.35; styles 3-fid. |
perianth bristles brown, equaling achene or tubercle, densely spinulose; anthers brown, 2–2.4 mm. |
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Achenes | whitish to olive or pale brown, sometimes spotted olive or red-brown, obovoid, trigonous (or subterete), angles prominent, 0.55–0.8 × 0.3–0.5 mm, apex constricted proximal to tubercle, smooth. |
often very variable within one plant, ovoid to obovoid or obpyriform, 1.5–2.5 × 1–1.2 mm, beak to 1 × 0.6 mm. |
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Tubercles | green or pale brown to red-brown, trigonous. |
when present pale to dark brown, pyramidal, to 0.5 × 0.3 mm. |
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Eleocharis microcarpa |
Eleocharis rostellata |
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Phenology | Fruiting late spring in south, summer–fall in north. | |||||
Habitat | Very wet calcareous or brackish fens, springs, shores | |||||
Elevation | 50–2400 m (200–7900 ft) | |||||
Distribution |
AL; FL; GA; IN; LA; MA; MD; MI; MS; NC; NJ; PA; SC; TN; TX; VA; West Indies
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AZ; CA; CT; DE; FL; ID; IL; IN; KS; LA; MA; MD; ME; MI; MN; MT; NC; NE; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TX; UT; VA; WA; WI; WY; BC; NS; ON; Mexico; West Indies (Cuba, Haiti, Puerto Rico)
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Discussion | Varieties 2 (2 in the flora). Specimens of Eleocharis brittonii and E. microcarpa without achenes are often difficult to distinguish. More detailed study of the four apparent entities across the two species is warranted. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis rostellata is highly competitive, often forming large monospecific colonies. The South American E. platypus C. B. Clarke is often treated as a synonym of E. rostellata. Eleocharis rostellata superfically closely resembles E. suksdorfiana in its culms, spikelets, and achenes, but differs in the absence of creeping rhizomes, presence of stoloniferous culms, absence of a flower in the proximal scale, and achene surface details. The collection of E. rostellata I have seen from Miami-Dade County, Florida, is from 1877. I have not seen vouchers for Archuleta County, Colorado, by H. D. Harrington (1954), or for the localities in Montana and South Carolina, which are based on the map in H. K. Svenson (1934). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 95. | FNA vol. 23, p. 90. | ||||
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Rostellatae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Scirpus rostellatus | |||||
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 312. (1836) | (Torrey) Torrey: Fl. New York 2: 347. (1843) | ||||
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