Flora of North America species comparison

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Eleocharis bolanderi

Eleocharis coloradoensis

Bolander's spikerush

dwarf spike-rush
Habit Plants perennial, densely tufted; rhizomes caudexlike, mostly hidden by culms and roots, short, 1.5–3 mm thick, hard, cortex persistent, internodes very short, scales not evident.
Culms

subterete, often with to 6 prominent ridges when dry, sulcate, 10–30 cm × 0.3–0.5 mm, firm to rigid, spongy.

Leaves

distal leaf sheaths persistent, not splitting, proximally brown, red, or stramineous, distally stramineous, green or reddish, papery, apex sometimes reddish, obtuse, rarely callose, tooth absent.

Spikelets

ovoid, 3–8 × 2–3 mm, apex acute to obtuse;

proximal scale amplexicaulous, entire;

subproximal scale with flower;

floral scales spreading in fruit, 8–30, 4–5 per mm of rachilla, dark brown to blackish, midrib regions often stramineous or greenish, ovate to lanceolate, 2–3 × 1.5 mm, apex entire, acute, often carinate in distal part of spikelet.

3–6 × 1–1.5 mm;

proximal scale 1/2 or less of spikelet length;

floral scales 6–25 per spikelet, mostly bright orange-brown, sometimes stramineous, 1.7–2.5 mm, apex subacute.
Flowers

perianth bristles 3–6, whitish to stramineous, stout to slender, often unequal, from rudimentary to 1/2 of achene length;

stamens 3;

anthers dark yellow to brown, 0.9–1.4 mm;

styles 3-fid.

perianth bristles mostly absent or rudimentary, occasionally to 5, 1/2 of achene length, very unequal;

anthers 0.6–0.9 mm.
Achenes

falling with scales, stramineous, rarely dark brown, ovoid to obpyriform, slightly to greatly compressed-trigonous, rarely thickly lenticular, angles prominent or abaxial angle obscure, 0.9–1.2 × 0.65–0.8 mm, apex narrowly to broadly truncate, neck short, often compressed more than body, at 20–30X finely rugulose with more than 20 horizontal ridges in a vertical series or reticulate or cancellate.

medium to dark brown, obovoid to obpyriform, thickly trigonous, rarely some biconvex, angles distinct to prominent, faces convex or some plane, 0.75–1.1 × 0.55–0.7 mm, apex narrowly truncate or tapered into tubercle, rugulose at 10X to finely rough at 30X.
Tubercles

whitish to brown, pyramidal, lower than wide, often 3-lobed as viewed from the top, 0.1–0.3 × 0.4–0.65 mm.

0.05–0.2 × 0.15 mm.
Tubers

terminating rhizomes, 2.5–4 × 0.7–1.5 mm, body (apart from apical bud) broadly oblong to orbicular, not markedly curved.

Eleocharis bolanderi

Eleocharis coloradoensis
Phenology Fruiting late spring–summer. Fruiting summer–fall (north), spring–fall (far south).
Habitat Fresh, often summer-dry meadows, springs, seeps, stream margins Fresh or brackish drying lake and pond margins, stream beds, flood plains, vernal pools, irrigation ditches, tidal wetlands
Elevation 1000–3400 m (3300–11200 ft) 0–2100 m (0–6900 ft)
Distribution
from FNA
CA; CO; ID; NV; OR; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CA; CO; IA; ID; KS; LA; MN; MO; MS; ND; NM; NV; OK; OR; SD; TX; UT; MB; SK; Mexico
Discussion

Eleocharis bolanderi is clearly distinct from E. montevidensis, from which it differs in its dense, tufted habit with short, caudexlike rhizomes, its leaf sheaths without a tooth, its achene and tubercle shapes, and its acute floral scales.

Specimens of Eleocharis bolanderi without rhizomes or achenes are easily confused with E. decumbens, which often may be distinguished by culms 0.5–2 mm wide, and spikelets with scales sometimes more than 3 mm long. The tubercles of E. bolanderi are usually poorly developed and much lower than wide; in E. decumbens they are usually well developed and about as high as wide.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Most authors, except C. L. Gilly (1941), H. L. Mason (1957), and R. R. Yeo (1980), have included Eleocharis coloradoensis in E. parvula or E. parvula var. anachaeta. In typical E. coloradoensis, which occurs from Saskatchewan south to Kansas and in California to 2100 m elevation, the achenes are usually distinctly rugulose or rough, often pitted-cellular, their apices usually truncate, and the tubercles are usually brown, often rudimentary, clearly distinct from the achene, and apparently partly sunken into the achene summit. Some plants from the southern Great Plains to the Mexican border, including the type of E. parvula var. anachaeta from Louisiana, may deserve taxonomic recognition. They differ from typical E. coloradoensis in having nearly smooth achenes with the apex tapered to a tubercle that is difficult to distinguish from the achene. C. L. Gilly (1941) separated these plants as E. membranacea (Buckley) Gilly; application of that name is doubtful because achenes are lacking from the type. R. R. Yeo (1980) studied the life-history of E. coloradoensis in the Sacramento Valley, California, and showed that it can be used to control several aquatic weeds in irrigation canals. The n = 4 count reported from Kansas under E. parvula var. anachaeta (Anonymous 1964) and on voucher specimens at GH and UC, is probably erroneous; the label on a duplicate voucher specimen at NDA includes the information “n = 3 II’s + a chain of IV” (i.e., n = 5). The record from Washington is somewhat doubtful because the specimen lacks achenes. Literature reports of E. parvula from Illinois and Tennessee may refer to E. coloradoensis; I have not seen specimens.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 23. FNA vol. 23, p. 106.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis Cyperaceae > Eleocharis > subg. Eleocharis > sect. Parvulae
Sibling taxa
E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, E. bella, E. bernardina, E. bicolor, E. bifida, 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. uniglumis, 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. cancellata, E. cellulosa, 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 E. montevidensis var. bolanderi Scirpus coloradoensis, E. parvula var. anachaeta
Name authority A. Gray: Proc. Amer. Acad. Arts 7: 392. (1868) (Britton) Gilly: Amer. Midl. Naturalist 26: 66. (1941)
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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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