Eleocharis montevidensis |
Eleocharis pachycarpa |
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Montevideo spike rush, sand spikerush |
black sand spikerush, broad fruit spikerush |
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Habit | Plants perennial, mat-forming; rhizomes evident, long, 0.7–2 mm thick, firm, cortex persistent, longer internodes 1–2 cm, scales often fugaceous, 6–8 mm, membranous, not fibrous. | 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 | terete or cross section elliptic or rectangular, with 5–10 blunt ridges when dry, 25–50 cm × 0.5–1.2 mm, firm to hard, spongy. |
erect to ascending or arching, acutely quadrangular, deeply sulcate, 7–50 cm × 0.3–0.5 mm, smooth, firm. |
Leaves | distal leaf sheaths persistent, not splitting, mostly proximally dark red, distally red to brown or green, thinly papery, apex usually red-brown, often callose, subtruncate to obtuse, tooth usually present on some or all culms, to 0.9 mm. |
distal leaf sheaths persistent, proximally brown or reddish, distally stramineous to green, thickly membranous, apex acute or subacute. |
Spikelets | usually ovoid or ellipsoid to subcylindric, rarely lanceoloid, 4–12 × (1.5–)2–3 mm, apex rounded to acute; proximal scale amplexicaulous or clasping over 3/4 of culm, entire; subproximal scale empty or with flower; floral scales appressed in fruit, 30–100, 6–10 per mm of rachilla, orange-brown, midrib regions often greenish, oblong to ovate, 1.5–2.5 × 1–1.5 mm, apex entire, broadly rounded, sometimes acute in distal part of spikelet, usually horizontally wrinkled and recurved, often carinate in distal part of spikelet. |
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(–7), stramineous to medium brown, stout, often unequal, much shorter than to equaling achene, rarely all rudimentary; stamens 3; anthers dark yellow to stramineous, 0.8–1.5 mm; styles 3-fid or some 2-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 | falling with scales, dark brown, obovoid to obpyriform, compressed trigonous, angles evident to obscure, 0.7–1 × 0.65–0.8 mm, neck absent to sometimes long, finely rugulose at 10–30X, over 20 horizontal ridges in vertical series, and/or minutely cancellate at 20–30X. |
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 | brown to whitish, pyramidal, as high as wide or sometimes greatly depressed, (0.1–)0.25–0.3 × 0.2–0.3 mm. |
stramineous, pyramidal, trigonous, usually acute, proximally trilobed, the lobes decurrent on achene, 0.5–0.9 × 0.7–0.9 mm. |
2n | = 20. |
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Eleocharis montevidensis |
Eleocharis pachycarpa |
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Phenology | Fruiting spring–fall. | Fruiting late spring–summer. |
Habitat | Wet soil, fresh ponds, lakes, streams, springs, seeps, marshes, ditches, grasslands | Fresh shores, streambeds, groundwater seeps |
Elevation | 0–2300 m (0–7500 ft) | 100–1400 m (300–4600 ft) |
Distribution |
AL; AZ; CA; FL; KS; LA; MS; NC; NM; OK; SC; TX; Mexico; South America
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CA; NV; South America (Argentina, Chile) [Introduced in North America; introduced in Australia]
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Discussion | The name Eleocharis montana was long misapplied to E. montevidensis. The type of E. palmeri, recognized as a species (H. K. Svenson 1957), is indistinguishable from specimens of E. montevidensis. Eleocharis montevidensis is extremely variable; the broadly rounded, usually wrinkled and recurved floral scales are diagnostic. Achenes often fail to form. Eleocharis montevidensis is apparently closely related to E. parishii, in which the floral scales are less densely placed on the rachilla and acute to rounded, and the spikelets are narrowly lanceoloid to cylindric. In the absence of achenes and rhizomes, some specimens of E. montevidensis are easily mistaken for E. tricostata. (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. 80. | FNA vol. 23, p. 91. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae |
Sibling taxa | ||
Synonyms | E. arenicola, E. montana subsp. montevidensis, E. palmeri | |
Name authority | Kunth: Enum. Pl. 2: 144. (1837) | E. Desvaux: in C. Gay, Fl. Chil. 6: 174. (1853) |
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