Eleocharis melanocarpa |
Eleocharis elongata |
|
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black-fruit spike-rush, black-fruit spikesedge |
slim spikerush |
|
Habit | Plants perennial; rhizomes 1–1.5 mm thick, soft, longer internodes 2–3 cm, scales 5–14 mm, tubers absent. | |
Culms | to 2 times wider than thick, 35–60(–70) cm × 0.5–1.3 mm, hard, usually with to 10 blunt ribs, at 20X often finely ridged and minutely granular. |
obscurely trigonous to terete; spikelet-bearing culms 16–80 cm × 0.5–1.5 mm; when submersed plants often forming numerous, filiform flaccid culms without spikelets, sometimes with whorls of slender branches, 0.1–0.3 mm wide, soft; sometimes septate-nodulose when aquatic, internally spongy, transverse septa incomplete. |
Leaves | distal leaf sheaths brown to reddish. |
distal leaf sheaths persistent or decaying, membranous, apex acute, often prolonged into translucent portion to 1 mm. |
Spikelets | 3–12 × 3–4 mm; proximal scale amplexicaulous, 3.5–4 mm, midrib region very broad and fleshy, apex entire; subproximal scale with a flower; floral scales 30–40, 8–10 per mm of rachilla, orange-brown to stramineous, midrib region stramineous, broadly ovate, papery or sometimes membranous, 3–4 × 2 mm, apex entire, rounded. |
not proliferous, (6–)9–24 × 1.4–2.2 mm; rachilla joints bearing prominent winglike remnants of floral scales; proximal scale with a flower, amplexicaulous, 2.5–4.1 mm; floral scales 7–26, 1–2 per mm of rachilla, green to stramineous or pale brown, often minutely dotted reddish, usually with conspicuous dark brown to blackish submarginal band, narrowly ovate, 3.5–4.5 × 2 mm, thickly papery, membranous toward margins. |
Flowers | perianth bristles present, sometimes rudimentary, brown, length variable, obscurely retrorsely spinulose; anthers brown, 1.7–2.2 mm. |
perianth bristles 6–7, whitish to stramineous or pale reddish brown, proximally slightly flattened, unequal, exceeding or rarely shorter than achene, 0.7–1.9 mm, retrorsely spinulose; anthers yellow to reddish, 1.7–1.9 mm; styles 3-fid. |
Achenes | subdeltoid in outline, sometimes broadly obpyriform, equilaterally trigonous, angles prominent, 0.9–1.2 × 0.7–1.1 mm, apex truncate. |
whitish, stramineous, or pale green, obovoid to obpyriform, compressed trigonous with adaxial face broadest, or biconvex, 0.65–1.4 × 0.5–0.8 mm, clearly sculptured at 10–15X, each face with 10–13 rows of rectangular, transversely elongated cells, apex constricted to short neck 0.2–0.25(–0.3) mm wide, wider at tubercle base. |
Tubercles | sessile, depressed-pyramidal, often apiculate, as wide as achene, 0.3–0.5 × 0.7–1.1 mm. |
dark brown, pyramidal, 0.2–0.5 × 0.2–0.4 mm. |
Eleocharis melanocarpa |
Eleocharis elongata |
|
Phenology | Fruiting summer. | Fruiting late spring–late fall. |
Habitat | Fresh, oligotrophic, acid, sandy or peaty, often drying shores, ponds, ditches | Sometimes drying ponds, lakeshores, marshes, creeks, canals, ditches |
Elevation | 10–300 m (0–1000 ft) | 10–50 m (0–200 ft) |
Distribution |
AL; FL; GA; IN; MA; MI; NC; NY; RI; SC; TX; VA
|
AL; FL; NC; TX; Mexico; Central America; South America |
Discussion | Eleocharis melanocarpa is reported from Rhode Island; I have not seen a voucher specimen. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis elongata sometimes grows with E. robbinsii; no intermediates are known. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 89. | FNA vol. 23, p. 117. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Melanocarpae | Cyperaceae > Eleocharis > subg. Limnochloa |
Sibling taxa | ||
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 311. (1836) | Chapman: Fl. South. U.S., 515. (1860) |
Web links |