Flora of North America species comparison

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Eleocharis uniglumis

Eleocharis brachycarpa

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

shortfruit 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, 0.2 mm thick, internodes to 4 mm, 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, 4-angled, sulcate, 5 cm × 0.1–0.2 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, colorless, translucent, apex narrowly acute.
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 × 1–2 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(–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 0.7–1.2 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.

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

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.

brownish, not appressed, mostly pyramidal, 0.1 × 0.1 mm.

Eleocharis uniglumis

Eleocharis brachycarpa
Phenology Fruiting summer. Fruiting winter–spring.
Habitat Mostly coastal, brackish (to fresh?) shores, marshes Wet soils
Elevation 0–2300 m (0–7500 ft) 0–20 m (0–100 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 (Tamaulipas)
[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 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. 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. 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. uniglumis, E. vivipara, E. wolfii
Synonyms Scirpus uniglumis, E. halophila, E. uniglumis var. halophila
Name authority (Link) Schultes: Mant. 2: 88. (1824) Svenson: Rhodora 31: 200, plate 190, fig. 34. (1929)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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