Eleocharis quadrangulata |
Eleocharis rostellata |
|
---|---|---|
four-angle spikerush, square-stem spike-rush, square-stem spikesedge |
beak spike-rush, beak spikesedge, walking sedge, walking spikerush |
|
Habit | Plants perennial; rhizomes 1.5–4 mm thick, soft to hard, longer internodes 3–8 cm, scales 5–10 mm, tubers absent. | Plants densely tufted, mat-forming by means of rooting culm tips. |
Culms | acutely quadrangular, (30–)45–105 cm × (1–)2–5.4 mm, soft to firm, internally spongy, transverse septa incomplete; plants never forming filiform, flaccid 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. |
Leaves | distal leaf sheaths persistent, membranous, apex narrowly acute to acuminate, sometimes prolonged into a bladelike portion to 8 cm. |
distal leaf sheaths not splitting abaxially, proximally dark red to brown, apex usually reddish. |
Spikelets | not proliferous, (15–)20–76 × 3–5(–6) mm; rachilla joints bearing obscure winglike remnants of floral scales; proximal scale empty, amplexicaulous, (1–)2.2–5.4 mm; floral scales (28–)45–135, 2–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, midrib region sometimes greenish, broadly obovate to ovate, (4–)4.5–6.2 × 2.8–5 mm, subcartilaginous, apex rounded to obtuse. |
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. |
Flowers | perianth bristles 6–7, whitish to brown, slender, often markedly unequal, shorter than achene or some equalling tubercle, sparsely retrorsely spinulose to smooth; anthers stramineous to red-brown, 2.3–2.9 mm; styles 3-fid, sometimes 2-fid. |
perianth bristles brown, equaling achene or tubercle, densely spinulose; anthers brown, 2–2.4 mm. |
Achenes | yellow or pale green to brown or purplish, biconvex, obovoid to obpyriform, 1.8–3 × 1.3–2 mm, almost smooth to markedly sculptured at 10–15X, each face with 19–38 rows of almost linear, transversely elongated cells, which are sometimes isodiametric at achene base, apex often constricted to neck 0.3–0.4 mm wide. |
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. |
Tubercles | dark brown or whitish, deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy. |
when present pale to dark brown, pyramidal, to 0.5 × 0.3 mm. |
Eleocharis quadrangulata |
Eleocharis rostellata |
|
Phenology | Fruiting early summer–winter. | Fruiting late spring in south, summer–fall in north. |
Habitat | Shallow water of fresh lake and pond shores, marshes | Very wet calcareous or brackish fens, springs, shores |
Elevation | 10–600 m (0–2000 ft) | 50–2400 m (200–7900 ft) |
Distribution |
AR; CA; CT; DE; FL; GA; IL; IN; KY; LA; MA; MI; MO; MS; NC; NJ; NY; OH; OK; OR; PA; SC; TX; VA; WI; WV; ON; s to c Mexico
|
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)
|
Discussion | We have not seen voucher specimens for the reports of Eleocharis quadrangulata from Kansas. Plants with greenish achenes, longer bristles, and longer anthers than the average are known from Tennessee. The tubercles of Eleocharis quadrangulata are often spongy as in E. obtusetrigona. (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.) |
Source | FNA vol. 23, p. 120. | FNA vol. 23, p. 90. |
Parent taxa | Cyperaceae > Eleocharis > subg. Limnochloa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Rostellatae |
Sibling taxa | ||
Synonyms | Scirpus quadrangulatus, E. quadrangulata var. crassior, Scirpus albomarginatus, Scirpus marginatus | Scirpus rostellatus |
Name authority | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 155. (1817) | (Torrey) Torrey: Fl. New York 2: 347. (1843) |
Web links |
|
|