Eleocharis vivipara
Eleocharis brittonii
sprouting spike-rush, umbrella hairgrass, viviparous spike-rush
Britton's spike-rush
often arching, often sering as stolons, broadly elliptic, (4–)7–38(–45) cm × (0.1–)0.3–0.7 mm, soft to firm.
ascending, quadrangular, sulcate (not sulcate in Eleocharis sp.
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 or fugaceous, pale brown or green, sometimes streaked red-brown, membranous to translucent, apex acute to acuminate.
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, ellipsoid to ovoid, terete, 2–10.5 × 1–2.8 mm, apex acute;
proximal scale empty, persistent, amplexicaulous, dissimilar to floral scales, slightly longer, often resembling an involucral bract, elliptic or lanceolate, 1.4–2.7 × 0.8–1.2 mm, apex rounded, midrib markedly thickened and broad;
subproximal scale with a flower;
floral scales spiraled, 13–76, 9–13 per mm of rachilla, colorless or pale brown, streaked or mottled pale brown to red-brown, midribs sometimes green, ovate, elliptic, or obovate, 0.8–2.2 × 0.5–1 mm, papery or membranous, midrib evident to prominent, apex rounded.
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 5–6 or absent, appressed to achene, white, vestigial to shorter than achene, to 0.3 mm;
spinules not evident at 45X;
stamens 2–3;
anthers 0.2–0.45 mm;
styles 3-fid.
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.
grayish to pale olive or yellowish, often minutely brown-spotted, obovoid, trigonous, angles prominent, 0.45–0.8 × 0.3–0.55 mm, apex constricted proximal to tubercle, smooth or finely pitted at 30X.
whitish, gray, brown, or greenish black, pyramidal, trigonous, 0.2–0.5 × 0.4–0.5 mm.
gray, green, or yellowish, birettaform, trigonous, 0.05–0.1 × 0.15–0.3 mm.
.
), 7–37 cm × 0.2–0.6 mm, soft to firm.
= 10.
Eleocharis vivipara
Eleocharis brittonii
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.)
Preliminary studies suggest that Eleocharis brittonii may be comprised of two entities that may warrant taxonomic recognition, perhaps at the species level. Typical E. brittonii is usually robust, with floral scales pale brown and papery, bristles well developed, and achenes to 0.8 mm, clearly pitted at 30X. It is known from Alabama, Florida, Georgia, Louisiana, Mississippi, New Jersey, and South Carolina. The second variant is usually small with floral scales whitish with red-brown markings, bristles absent or poorly developed, and achenes not more than 0.6 mm, smooth at 30X. We have annotated specimens of this second variant E. sp. aff. brittonii, known from Arkansas, Florida, Georgia, Louisiana, Mississippi, Tennessee, and Texas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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