Eleocharis rostellata |
Eleocharis brachycarpa |
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beak spike-rush, beak spikesedge, walking sedge, walking spikerush |
shortfruit spikerush |
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Habit | Plants densely tufted, mat-forming by means of rooting culm tips. | Plants annual, densely cespitose; rhizomes obscured among culm bases, 0.2 mm thick, internodes to 4 mm, scales not evident. |
Culms | 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. |
mostly ascending, 4-angled, sulcate, 5 cm × 0.1–0.2 mm, soft. |
Leaves | distal leaf sheaths not splitting abaxially, proximally dark red to brown, apex usually reddish. |
distal leaf sheaths persistent, colorless, translucent, apex narrowly acute. |
Spikelets | 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. |
ovoid, 2–3 × 1–2 mm, apex blunt; floral scales 10–30, ca. 10 per mm of rachilla, orange-brown to stramineous with broad colorless margin, midrib region stramineous, lanceolate, folded lengthwise, 1.5–2 × 0.8–1 mm, midrib prominent, apex acuminate. |
Flowers | perianth bristles brown, equaling achene or tubercle, densely spinulose; anthers brown, 2–2.4 mm. |
perianth bristles absent; anthers 0.7–1.2 mm. |
Achenes | 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. |
whitish, broadly obpyriform, much less than 2 times longer than wide, angles and longitudinal ridges ca. 6, obscure, 0.4 × 0.3 mm, apex blunt, trabeculae 20, indistinct, crowded. |
Tubercles | when present pale to dark brown, pyramidal, to 0.5 × 0.3 mm. |
brownish, not appressed, mostly pyramidal, 0.1 × 0.1 mm. |
Eleocharis rostellata |
Eleocharis brachycarpa |
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Phenology | Fruiting late spring in south, summer–fall in north. | Fruiting winter–spring. |
Habitat | Very wet calcareous or brackish fens, springs, shores | Wet soils |
Elevation | 50–2400 m (200–7900 ft) | 0–20 m (0–100 ft) |
Distribution |
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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TX; Mexico (Tamaulipas) |
Discussion | 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.) |
Of conservation concern. Eleocharis brachycarpa is unique among the North American members of subg. Scirpidium in its floral scales, which are markedly spreading in fruit, often apparently decussate when pressed, narrowly lanceolate, and folded lengthwise so that they do not press open and flat. It is apparently very rare and local. It is admitted to the flora only on the basis of labels on a paratype (Berlandier 996) and on Berlandier 2426, both of which read “In locis paludosis – De Matamoros a las Nueces [River, Texas], Ap. 1834.” H. K. Svenson (1929) mistranscribed the locality “Nueces,” publishing it as “Mueres.” We have also seen a specimen from Mexico, Tamaulipas, 24 mi. N of San Fernando, edges of resacas, elev. 15 m, 1959, M.C. Johnston 4882C (TEX). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 90. | FNA vol. 23, p. 111. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Rostellatae | Cyperaceae > Eleocharis > subg. Scirpidium |
Sibling taxa | ||
Synonyms | Scirpus rostellatus | |
Name authority | (Torrey) Torrey: Fl. New York 2: 347. (1843) | Svenson: Rhodora 31: 200, plate 190, fig. 34. (1929) |
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