Eleocharis microcarpa |
Eleocharis tuberculosa |
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small-fruit spikesedge, smallfruit spikerush |
cone-cup spikerush, long-tubercled spikerush, long-tubercled spikesedge |
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Habit | Plants usually annual, tufted, sometimes mat-forming via proliferating and arching inflorescences (stoloniferous), sometimes entirely vegetative; rhizomes absent. | Plants perennial, forming dense clumps, not stoloniferous. | ||||
Rhizomes | present or not, caudexlike, ascending, 1 mm thick; internodes and scales hidden by crowded culms, not evident. |
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Culms | often ascending or arching, quadrangular or broadly elliptic, 2–40 cm × 0.1–0.4(–0.6) mm, soft. |
elliptic or sometimes circular, with several rounded ridges and sulcate when dry, 15–75 cm × 0.3(–1.5) mm, firm, minutely granular at 10X. |
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Leaves | distal leaf sheaths persistent or disintegrating, pale brown, green or red-brown, streaked or mottled red-brown or purple, translucent, membranous, apex narrowly acute. |
distal leaf sheaths persistent; stramineous to green, often minutely red-spotted, papery to membranous, apex subacute to narrowly acute, often with tooth-like callus. |
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Spikelets | basal spikelets absent; often proliferous, ovoid to ellipsoid or lanceoloid, terete, 2–10.7 × 1–2 mm, apex acute; proximal scale empty, persistent, amplexicaulous, dissimilar to floral scales, often longer, often resembling an involucral bract, ovate to lanceolate, midrib markedly thickened and broad and often prolonged beyond lamina; subproximal scale with flower; floral scales spiraled, colorless, whitish, or pale brown, streaked or mottled red-brown or purple, midribs green and red-brown or green and purple, ovate to elliptic, 0.8–1.5 × 0.4–0.8 mm, membranous, midrib obscure to prominent. |
basal spikelets absent; never proliferous, ovoid, terete, 5–15 × 2.5–4 mm, apex acute; proximal scale empty, deciduous, clasping 1/2 of culm, similar to floral scales; subproximal scale often empty; floral scales spiraled, 10–30, 5–6 per mm of rachilla, pale orange-brown, midribs green, broadly ovate, 2.5–4 × 1.5–2.5 mm, central area and often flanks papery to cartilaginous (or membranous), midrib evident, apex broadly rounded to obtuse. |
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Flowers | perianth bristles present or sometimes apparently absent; stamens 3; anthers 0.15–0.35; styles 3-fid. |
perianth bristles 5–6, bright brown, stout, slightly shorter than to equaling tubercle; spinules rarely absent, dense, variably from divaricate to antrorse, very short, and blunt to acute, to often much longer and retrorse, sharply acute; stamens 2–3; anthers 0.5–1 mm; styles 3-fid. |
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Achenes | whitish to olive or pale brown, sometimes spotted olive or red-brown, obovoid, trigonous (or subterete), angles prominent, 0.55–0.8 × 0.3–0.5 mm, apex constricted proximal to tubercle, smooth. |
medium brown, obovoid to obpyriform, compressed (often obscurely) trigonous, angles evident, 0.9–1.7 × 0.8–2 mm; apex often constricted proximal to tubercle, very coarsely cancellate at 10X, each face with 8–10 longitudinal rows of large depressions. |
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Tubercles | green or pale brown to red-brown, trigonous. |
bone-white to pale orange-brown, often red-spotted, subpyramidal, cross section plano-convex, 0.9–1.7(–2.4) × 0.7–1.2–2(–2.2) mm, at least as high and wide as achene, spongy, apex rounded, often with an abaxial acute projection. |
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Eleocharis microcarpa |
Eleocharis tuberculosa |
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Phenology | Fruiting spring (in south)–fall. | |||||
Habitat | Wet soil, freshwater, ponds, lakeshores, streams, meadows, pine woods, grasslands, disturbed places, bogs | |||||
Elevation | 0–500 m (0–1600 ft) | |||||
Distribution |
AL; FL; GA; IN; LA; MA; MD; MI; MS; NC; NJ; PA; SC; TN; TX; VA; West Indies
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AL; AR; FL; GA; LA; MA; MS; NC; NJ; SC; TN; TX; NS
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Discussion | Varieties 2 (2 in the flora). Specimens of Eleocharis brittonii and E. microcarpa without achenes are often difficult to distinguish. More detailed study of the four apparent entities across the two species is warranted. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis tuberculosa evidently is closely related to E. tortilis, from which it differs in its larger tubercles, culms that are always elliptic in cross section, and perianth bristle spinules that are often divaricate to antrorse and often blunt. The specimens of E. tuberculosa from throughout its range which are like E. tortilis in having retrorsely spinulose perianth bristles have been named E. tuberculosa forma retrorsa Svenson (type from Massachusetts). Plants from Nova Scotia with nearly smooth bristles have been named E. tuberculosa var. pubnicoensis Fernald and E. tuberculosa forma pubnicoensis (Fernald) Svenson. We have not seen voucher specimens for literature reports of Eleocharis tuberculosa from Connecticut, Delaware, Maine, Maryland, New Hampshire, New York, Pennsylvania, Rhode Island, or Virginia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 95. | FNA vol. 23, p. 92. | ||||
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Scirpus tuberculosus, E. tuberculosa var. pubnicoensis | |||||
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 312. (1836) | (Michaux) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 152. (1817) | ||||
Web links |