Eleocharis parvula |
Eleocharis cancellata |
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dwarf spikerush, dwarf spikesedge, little-head spike-rush, little-head spikesedge, small spike-rush, éléocharide naine |
Arizona spikerush |
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Habit | Plants annual(?), densely cespitose; rhizomes obscured among culm bases, delicate, internodes very short, scales not evident. | |
Culms | mostly ascending, terete or 4-angled, 2 cm × 0.2–0.3 mm, soft. |
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Leaves | distal leaf sheaths persistent, greenish to whitish, translucent, membranous, apex blunt. |
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Spikelets | 2–4 × 1–2 mm, sometimes absent in deeper water; proximal scale 1/2 or more of spikelet length; floral scales 6–10 per spikelet, 1.4–2.7 mm, commonly entirely stramineous, apex rounded to subacute. |
ovoid, 2–3 × 1 mm, apex acute; floral scales 7–10, 5 per mm of rachilla, bright brown or colorless, medially greenish, ovate to lanceolate, not folded lengthwise, 0.8–1.2(–1.5) × 0.6–0.8 mm, midrib obscure to slightly keeled, apex acute to acuminate. |
Flowers | perianth bristles 6, stramineous, fairly stout to slender, usually equaling achene to slightly exceeding tubercle, sometimes unequal and some 1/2 of achene, very rarely rudimentary, minutely retrorsely spinulose; anthers 0.7–1.2 mm. |
perianth bristles absent; anthers orange-brown, 0.2–0.3 mm. |
Achenes | stramineous, sometimes pale brown, obovoid to obpyriform, thickly trigonous, angles distinct, faces concave to plane, rarely convex, 0.9–1.2 × 0.55–0.75 mm, apex tapered, smooth or faintly rough at 30X. |
brownish, broadly ovoid to obpyriform, much less than 2 times longer than wide, with angles plus longitudinal ridges ca. 6, rather obscure, 0.5–0.55 × 0.35 mm, apex blunt, trabeculae 15–20, distinct. |
Tubers | terminating rhizomes usually markedly J- or horseshoe-shaped, body (apart from apical bud) oblong, 2–2.5(–5) × 0.5–1 mm; tubers among culm bases straight, narrowly fusiform, 4–5 mm. |
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Tubercles | 0.1–0.2 × 0.15 mm. |
grayish or brownish, often appressed, mostly pyramidal, 0.1 × 0.1 mm. |
2n | = 10 (Europe). |
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Eleocharis parvula |
Eleocharis cancellata |
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Phenology | Fruiting summer–fall (north) or late winter–fall (far south). | Fruiting fall (Sep). |
Habitat | Brackish or saline, mostly coastal tidal marshes, shores, mud flats, swamps, ponds, ditches | Wet springy places |
Elevation | 0–600 m (0–2000 ft) | 1700 m (5600 ft) |
Distribution |
AL; AR; CA; CT; FL; GA; IL; IN; KS; LA; MA; MD; ME; MI; MO; MS; NC; NJ; NY; OH; OR; SC; VA; WA; BC; NB; NL; NS; QC; Mexico; Central America (Nicaragua); Eurasia
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TX; Mexico (San Luis Potosí) |
Discussion | Plants without well-developed bristles are otherwise typical Eleocharis parvula. S.-O. Strandhede and R. M. T. Dahlgren (1968) provided a detailed description from Scandinavia; the mostly curved tubers of North American plants are differently shaped than the ovoid, mostly nearly straight tubers illustrated by them. Eleocharis parvula is very uncommon inland. Plants lacking spikelets and having rather broad culms with evident aerenchyma (E. parvula forma spongiosa Fassett) that are submerged in tidal zones closely resemble small plants of Sagittaria graminea. Eleocharis parvula has also been reported from North Dakota, South America, and Africa; I have not seen specimens. Plants without achenes or tubers cannot be reliably identified to species. Literature reports from Cuba, Mexico, and Venezuela may be based on specimens of E. coloradoensis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Eleocharis cancellata is very similar to E. bella. The achenes of E. cancellata are relatively broader in relation to their length, the angles and ridges obscure and fewer, and the trabeculae very distinct and faintly wavy at 35X. R. McVaugh and W. R. Anderson (1974+, vol. 13) mentioned possible intermediates with E. acicularis from Mexico. Eleocharis cancellata has been reported from the flora area from three collections: (1) Texas, Jeff Davis County, A. Brant et al. 2237, 1993, originally identified as E. bella; (2) southwestern Texas or northern Mexico (probably from near San Antonio), Parry & Palmer 912, 1879–1880; and (3) Arizona, Santa Cruz County(?), C. Wright 1937, collected in 1851. Although it was also reported from New Mexico (H. K. Svenson 1929), E. cancellata probably does not occur there (R. McVaugh and W. R. Anderson 1974+, vol. 13). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 106. | FNA vol. 23, p. 111. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Parvulae | Cyperaceae > Eleocharis > subg. Scirpidium |
Sibling taxa | ||
Synonyms | Scirpus parvulus, E. pygmaea, S. nanus | |
Name authority | (Roemer & Schultes) Link ex Bluff Nees: Comp. Fl. German. ed. 2, 1: 93. (1836) | S. Watson: Proc. Amer. Acad. Arts 18: 170. (1883) |
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