Eleocharis rostellata |
Eleocharis retroflexa |
|
---|---|---|
beak spike-rush, beak spikesedge, walking sedge, walking spikerush |
coastal plain spikerush |
|
Habit | Plants densely tufted, mat-forming by means of rooting culm tips. | Plants annual, tufted, mat-forming, often stoloniferous, sometimes entirely vegetative; rhizomes absent. |
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. |
erect, ascending or arching, pentagonal, sulcate, 1.5–10 cm × 0.2–0.3 mm [larger], soft. |
Leaves | distal leaf sheaths not splitting abaxially, proximally dark red to brown, apex usually reddish. |
distal leaf sheaths persistent or disintegrating, pale brown to green, red-spotted [mostly red-brown], membranous; apex acuminate. |
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. |
basal spikelets usually present, bisexual; often proliferous, ellipsoid or obovoid, laterally compressed, 1.7–3.9 × 1.2–2 mm, apex acute; proximal scale empty or with a flower, deciduous, amplexicaulous, similar to floral scales (sometimes 2.4–2.9 mm); subproximal scale with a flower; floral scales clearly distichous, 2–6 [or more], 4–6 per mm of rachilla, pale brown [marked red-brown], ovate or elliptic, 1.8–2.5 × 0.8–1.4 mm, membranous, apex rounded to obtuse, midribs green, keeled. |
Flowers | perianth bristles brown, equaling achene or tubercle, densely spinulose; anthers brown, 2–2.4 mm. |
perianth bristles 6, colorless or pale brown, shorter than achenes; spinules not evident at 45X; stamens 3; anthers (0.55–)0.7 mm; styles 3-fid. |
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. |
stramineous (to cream), obovoid, trigonous or subterete, not compressed, angles prominent, 0.8 × 0.5–0.55 mm, apex not constricted proximal to tubercle, coarsely cancellate or honeycomb-reticulate at 10–15X. |
Tubercles | when present pale to dark brown, pyramidal, to 0.5 × 0.3 mm. |
red-brown, pyramidal, trigonous, proximally clearly to obscurely 3-lobed, lobes decurrent on achene angles, 0.3–0.35 × 0.3–0.4 mm. |
Eleocharis rostellata |
Eleocharis retroflexa |
|
Phenology | Fruiting late spring in south, summer–fall in north. | Fruiting summer. |
Habitat | Very wet calcareous or brackish fens, springs, shores | Freshwater ponds, stream banks, marshes, sandy or muddy soils |
Elevation | 50–2400 m (200–7900 ft) | 0–10 m (0–0 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)
|
AL; Mexico; Central America; South America; West Indies; Bermuda; Asia (including Indonesia); Pacific Islands; Australia |
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.) |
We have seen only one collection of Eleocharis retroflexa from the flora area (Mobile, Alabama, in 1896, US). Other populations are likely in the United States Gulf States. The broad-shouldered, strongly sculptured achenes, trilobed, decurrent tubercles, and basal spikelets are distinctive. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 90. | FNA vol. 23, p. 98. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Rostellatae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae |
Sibling taxa | ||
Synonyms | Scirpus rostellatus | Scirpus retroflexus, Baeothryon retroflexum, Chaetocyperus niveus, Chaetocyperus polymorphus var. depauperatus, Chaetocyperus rugulosus, Chaetocyperus viviparus, Cyperus depauperatus, E. depauperata |
Name authority | (Torrey) Torrey: Fl. New York 2: 347. (1843) | (Poiret) Urban: Symb. Antill. 2: 165. (1900) |
Web links |
|