Eleocharis vivipara |
Eleocharis pachycarpa |
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sprouting spike-rush, umbrella hairgrass, viviparous spike-rush |
black sand spikerush, broad fruit spikerush |
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Habit | Plants perennial, short-rhizomatous, forming dense clumps, often entirely vegetative; rhizomes caudexlike, ascending, internodes and scales hidden by crowded culms and sheaths, 0.5 mm thick. | Plants perennial, forming dense clumps, often stoloniferous. |
Rhizomes | present, caudexlike, mostly concealed by crowded culms, vertical or ascending, 2 mm thick; internodes very short, scales disintegrating to fibers, 4 mm, papery. |
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Culms | often arching, often sering as stolons, broadly elliptic, (4–)7–38(–45) cm × (0.1–)0.3–0.7 mm, soft to firm. |
erect to ascending or arching, acutely quadrangular, deeply sulcate, 7–50 cm × 0.3–0.5 mm, smooth, firm. |
Leaves | distal leaf sheaths persistent or disintegrating, yellowish to pale brown, sometimes mottled or wholly red-brown, membranaous to papery, apex acute to narrowly obtuse. |
distal leaf sheaths persistent, proximally brown or reddish, distally stramineous to green, thickly membranous, apex acute or subacute. |
Spikelets | basal spikelets absent; usually proliferous, ovoid to ellipsoid to linear or terete, 3.3–9.6 × 1.2–2.3 mm, apex acute; proximal scale empty, persistent, amplexicaulous, similar to floral scales (usually slightly longer, midrib broadly green); subproximal scale with a flower; floral scales spiraled, 5–25, 4–8 per mm of rachilla, pale brown, usually spotted, streaked or mottled red-brown to purple, midribs green or green and red-brown, elliptic to obovate, 1.8–2.7 × 1–1.5 mm, membranous to chartaceous (papery), midrib evident to prominent, apex rounded to obtuse. |
basal spikelets absent; often proliferous, ovoid, terete, 3–10 × 2–3 mm, apex acute; proximal scale empty, amplexicaulous, similar to floral scales; subproximal scale with a flower; floral scales spiraled, 8–15, 4 per mm of rachilla, orange-brown, midrib region broadly stramineous or like flanks, ovate, 2–3 × 1.2–2 mm, membranous, midrib evident to prominent, apex acute (to rounded). |
Flowers | perianth bristles 5–6, red-brown (proximally often white), shorter than to equaling tubercle, rarely longer, 0.9–1.3(–2) mm; spinules sparse, retrorse, sharply acute; stamens 3; anthers yellow, 0.8–1.8 mm; styles 3-fid. |
perianth bristles 6 or fewer, stramineous, unequal, some or most equaling achene, spinules obscure, sparse, retrorse, sharply acute. |
Stamens | 3; anthers 1.2–1.5 mm. |
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Styles | 3-fid. |
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Achenes | gray or greenish, obovoid or obpyriform, trigonous, angles very prominent, 0.6–0.9 × 0.55–0.8 mm, apex constricted proximal to tubercle, finely honeycomb-reticulate at 10–20X, each face with 20 or more rows of evident enlarged cells. |
stramineous, broadly obpyriform, equilaterally trigonous, angles evident, blunt, 0.9–1.1 × 0.7–0.9 mm, apex nearly truncate, smooth or obscurely papillose or rugulose at 20X. |
Tubercles | whitish, gray, brown, or greenish black, pyramidal, trigonous, 0.2–0.5 × 0.4–0.5 mm. |
stramineous, pyramidal, trigonous, usually acute, proximally trilobed, the lobes decurrent on achene, 0.5–0.9 × 0.7–0.9 mm. |
Eleocharis vivipara |
Eleocharis pachycarpa |
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Phenology | Fruiting spring–fall. | Fruiting late spring–summer. |
Habitat | Sandy and peaty soils, ditches, pond margins, shallow waters bordering pine-flatwoods and pine-palmetto scrub | Fresh shores, streambeds, groundwater seeps |
Elevation | 0–80 m (0–300 ft) | 100–1400 m (300–4600 ft) |
Distribution |
AL; FL; GA; LA; NC; SC; VA
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CA; NV; South America (Argentina, Chile) [Introduced in North America; introduced in Australia]
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Discussion | Most specimens of Eleocharis vivipara are from Florida. Identification of vegetative (often aquatic) specimens is sometimes tentative. Eleocharis vivipara is often confused with E. microcarpa and E. brittonii, and sometimes with E. baldwinii. The red-spotted band at the sheath apex and the gray, cancellate achenes are characteristic of E. vivipara. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
H. K. Svenson (1957) placed Eleocharis pachycarpa in ser. Sulcatae Svenson. Contrary to his statement that perianth bristles are often lacking, they are present in all of the specimens we have seen. Superficially similar to E. bolanderi, from which it may readily be distinguished by its oblique leaf sheath summits, 4-angled culms, pyramidal tubercles, and often proliferating spikelets. The earliest North American specimen we have seen was collected in 1919 in Tuolumne County, California. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 93. | FNA vol. 23, p. 91. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae |
Sibling taxa | ||
Synonyms | Chlorocharis vivipara, E. curtisii | |
Name authority | Link: Hort. Berol. 1: 283. (1827) | E. Desvaux: in C. Gay, Fl. Chil. 6: 174. (1853) |
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