Eleocharis atropurpurea |
Eleocharis brachycarpa |
|
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purple spike-rush |
shortfruit spikerush |
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Habit | Plants tufted, without creeping rhizomes. | Plants annual, densely cespitose; rhizomes obscured among culm bases, 0.2 mm thick, internodes to 4 mm, scales not evident. |
Culms | 2–12(–19) cm × 0.2–0.4 mm. |
mostly ascending, 4-angled, sulcate, 5 cm × 0.1–0.2 mm, soft. |
Leaves | distal leaf sheaths firm, distally tightly sheathing, apex acute. |
distal leaf sheaths persistent, colorless, translucent, apex narrowly acute. |
Spikelets | ovoid to ellipsoid, 2–6(–8) × 1–2.5 mm, apex acute; proximal scale with or without flower, not amplexicaulous; floral scales to 100, 15–19 per mm of rachilla, often loosely appressed, dark red-brown to stramineous, ovate to elliptic, 0.6–1.3 × 0.3–0.7 mm, membranous, apex rounded to acute. |
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. |
Flowers | perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous; styles 2-fid. |
perianth bristles absent; anthers 0.7–1.2 mm. |
Achenes | black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X. |
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. |
Tubercles | stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute. |
brownish, not appressed, mostly pyramidal, 0.1 × 0.1 mm. |
2n | = 20. |
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Eleocharis atropurpurea |
Eleocharis brachycarpa |
|
Phenology | Fruiting summer–fall (Jun–Sep). | Fruiting winter–spring. |
Habitat | Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields | Wet soils |
Elevation | 0–1800 m (0–5900 ft) | 0–20 m (0–100 ft) |
Distribution |
AL; CA; FL; GA; IA; KS; LA; MI; MO; NC; NE; NM; OK; SC; TX; WA; BC; Mexico; Central America; South America; West Indies; Europe (naturalized); Asia; Africa; Pacific Islands
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TX; Mexico (Tamaulipas) |
Discussion | Eleocharis atropurpurea has been reported from Colorado, Montana, and Virginia; I have not seen voucher specimens. (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.) |
Source | FNA vol. 23, p. 102. | FNA vol. 23, p. 111. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae | Cyperaceae > Eleocharis > subg. Scirpidium |
Sibling taxa | ||
Synonyms | Scirpus atropurpureus | |
Name authority | (Retzius) J. Presl & C. Presl: in C. B. Presl, Reliq. Haenk. 1: 196. (1828) | Svenson: Rhodora 31: 200, plate 190, fig. 34. (1929) |
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