Eleocharis montevidensis
Eleocharis brachycarpa
Montevideo spike rush, sand spikerush
shortfruit spikerush
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.
mostly ascending, 4-angled, sulcate, 5 cm × 0.1–0.2 mm, soft.
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, colorless, translucent, apex narrowly acute.
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.
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.
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 absent;
anthers 0.7–1.2 mm.
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.
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.
brown to whitish, pyramidal, as high as wide or sometimes greatly depressed, (0.1–)0.25–0.3 × 0.2–0.3 mm.
brownish, not appressed, mostly pyramidal, 0.1 × 0.1 mm.
= 20.
Eleocharis montevidensis
Eleocharis brachycarpa
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.)
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.)
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