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creeping spike-rush, one-glumed spikesedge, onescale spikerush, slender spike-rush, éléocharide unigume

Arizona spikerush

Habit Plants perennial, mat-forming; rhizomes evident, long, 0.3–1 mm thick, soft to firm, cortex often fugaceous, longer internodes 10–25 mm, scales fugaceous, 5–6 mm, membranous, not fibrous. Plants annual(?), densely cespitose; rhizomes obscured among culm bases, delicate, internodes very short, scales not evident.
Culms

terete, often with some blunt ridges when dry, (5–)10–60 cm × 0.2–1.5 mm, firm, internally spongy.

mostly ascending, terete or 4-angled, 2 cm × 0.2–0.3 mm, soft.

Leaves

distal leaf sheaths persistent, not splitting, proximally red, distally stramineous to green, often callose, thinly papery to thickly membranous, apex often dark red-brown, obtuse to subacute, tooth absent.

distal leaf sheaths persistent, greenish to whitish, translucent, membranous, apex blunt.

Spikelets

ovoid to lanceoloid, 5–10 × 2–3(–4) mm, apex acute;

proximal scale amplexicaulous, entire;

subproximal scale with flower;

floral scales often spreading in fruit, 10–20, 3–4 per mm of rachilla, brown to often red-brown, midrib regions mostly stramineous to green, broadly ovate, 3–4 × 1.8–2.5 mm, entire, apex acute to obtuse, often some carinate in distal part of spikelet.

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 0–4(–5), light brown to stramineous, stout, usually unequal, rudimentary to equaling achene;

stamens 3;

anthers dark yellow to stramineous, 1.2–2 mm;

styles 2-fid.

perianth bristles absent;

anthers orange-brown, 0.2–0.3 mm.

Achenes

not persistent, dark yellow or medium or dark brown, ellipsoid, obovoid, or obpyriform, biconvex, angles obscure, 1.3–1.8 × 1–1.4 mm, apex rounded, neck absent or short, smooth at 30X, or sometimes finely rugulose at 10–20X with 20 or more horizontal ridges in vertical series.

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.

Tubercles

brown to whitish, pyramidal, much higher than wide to slightly depressed, sometimes spongy and with vertical rows of depressions, 0.4–0.8 × 0.3–0.8 mm.

grayish or brownish, often appressed, mostly pyramidal, 0.1 × 0.1 mm.

Eleocharis uniglumis

Eleocharis cancellata

Phenology Fruiting summer. Fruiting fall (Sep).
Habitat Mostly coastal, brackish (to fresh?) shores, marshes Wet springy places
Elevation 0–2300 m (0–7500 ft) 1700 m (5600 ft)
Distribution
from FNA
CO; DE; MA; ME; NC; ND; NE; NH; NJ; NM; NV; NY; RI; SD; UT; VA; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; Eurasia
[WildflowerSearch map]
from FNA
TX; Mexico (San Luis Potosí)
[BONAP county map]
Discussion

Plants treated as Eleocharis uniglumis fall within the large morphologic variation of Eurasian E. uniglumis. Two subspecies and 3 varieties were recognized for northern Europe (S.-O. Strandhede 1966), and five species that were recognized by I. D. Zinserling (1935) were placed in synonymy under E. uniglumis (S.-O. Strandhede 1966). Recognition of infraspecific taxa within North American E. uniglumis is premature. Plants commonly called E. halophila or E. uniglumis var. halophila, found mostly in Atlantic Coastal brackish habitats, have floral scales that are usually narrower and more densely placed on the rachilla than plants usually called E. uniglumis, which are found mostly in the interior; some plants are intermediate in expression of these characters. The achene and tubercle shape characters used by M. L. Fernald (1950) to distinguish E. uniglumis from E. halophila are not valid. In North America, E. uniglumis is difficult to separate from E. erythropoda and E. kamtschatica, in both of which the spikelets have only the proximal scale without a flower (empty) and the proximal scale completely amplexicaulous. Eleocharis uniglumis differs from E. erythropoda only in its broader floral scales, which are less densely placed on the rachilla; it differs from E. kamtschatica only in its smaller tubercles. It is also difficult to separate from some specimens of E. macrostachya in which the spikelets have proximal scales that are sometimes completely amplexicaulous; such plants differ from E. uniglumis only in the absence of a flower in the axil of the subproximal scale of some of the spikelets. I have not seen voucher specimens for the chromosome numbers of 2n = 27 and 28 reported by S.-O. Strandhede (1967) from Massachusetts and Nebraska, which are lower than the 2n = (44–)46(47–88) reported for Europe (S.-O. Strandhede 1965).

(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. 76. FNA vol. 23, p. 111.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis Cyperaceae > Eleocharis > subg. Scirpidium
Sibling taxa
E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cancellata, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. radicans, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. vivipara, E. wolfii
E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, E. bolanderi, E. brachycarpa, E. brittonii, E. cellulosa, E. coloradoensis, E. compressa, E. cylindrica, E. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, E. fallax, E. flavescens, E. geniculata, E. intermedia, E. interstincta, E. kamtschatica, E. lanceolata, E. macrostachya, E. mamillata, E. melanocarpa, E. microcarpa, E. minima, E. montana, E. montevidensis, E. nana, E. nigrescens, E. nitida, E. obtusa, E. obtusetrigona, E. occulta, E. ovata, E. pachycarpa, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. radicans, E. ravenelii, E. retroflexa, E. reverchonii, E. robbinsii, E. rostellata, E. suksdorfiana, E. tenuis, E. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. vivipara, E. wolfii
Synonyms Scirpus uniglumis, E. halophila, E. uniglumis var. halophila
Name authority (Link) Schultes: Mant. 2: 88. (1824) S. Watson: Proc. Amer. Acad. Arts 18: 170. (1883)
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