Flora of North America species comparison

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Eleocharis bella

Eleocharis decumbens

beautiful spikerush, delicate spikerush, pretty spikerush

decumbent spikerush
Habit Plants annual, rarely perennial, usually densely tufted; rhizomes rarely evident, 0.2–0.3 mm thick, internodes 1–5 mm, scales not evident. Plants perennial, densely tufted; rhizomes often hidden by culms and roots, fairly long, 3–4 mm thick, hard, cortex persistent, longer internodes from very short to 5 mm, scales usually clearly evident, disintegrating to fibers, 20–25 mm, papery.
Culms

often ascending or spreading, 4-angled or sometimes terete, sometimes sulcate, 1–7 cm × 0.2–0.3 mm, soft to firm.

terete, often with 10–18 blunt ridges when dry, 10–50 cm × 0.3–2 mm, firm to rigid, spongy.
Leaves

sheaths stramineous, distal sheaths often splitting abaxially, slightly inflated distally, oblique, apex acute.

distal leaf sheaths persistent, not splitting, proximally brown or reddish, distally stramineous, brown, reddish or green, often inflated, papery, apex mostly dark red-brown, subtruncate to obtuse, often callose, tooth absent.
Spikelets

ovoid, 1.5–4 × 0.8–2 mm, apex acute;

floral scales 4–15, 8 per mm of rachilla, colorless or reddish brown, midrib region green, ovate-lanceolate, not folded lengthwise, 1–1.5 × 0.5–0.7 mm, mibrib obscure to somewhat keeled, apex narrowly acute to acuminate, slightly recurved.

ovoid, 3–8 × 2–2.5 mm, apex acute;

proximal scale amplexicaulous, entire;

subproximal scale empty or with flower;

floral scales appressed in fruit, 10–20, 3 per mm of rachilla, orange-brown, midrib regions often greenish, ovate, 3–3.5 × 1.5 mm, apex entire, acute, often carinate in distal part of spikelet.
Flowers

perianth bristles absent;

anthers 0.3–0.5 mm.

perianth bristles 6, stramineous, stout, nearly equal, mostly equaling or exceeding tubercle, (0.5–)1–2.2 mm, prominently retrorsely spinulose;

stamens 3(?);

anthers dark yellow to stramineous, 1.2–1.5;

styles 3-fid.
Achenes

with angles and longitudinal ridges ca. 6–10, rather prominent, broadly ovoid, less than 2 times longer then wide, (0.55–)0.65–0.75 × 0.3–0.4 mm, apex blunt, trabeculae distinct, 20–30.

falling with scales, dark brown, obpyriform, nearly eqilaterally- to greatly compressed-trigonous, angles slightly prominent, 1–1.3 × 0.75–0.9 mm, neck absent or short, finely rugulose at 20X with more than 20 horizontal ridges in vertical series, or reticulate or cancellate at 20–30X.
Tubercles

grayish, mostly appressed, pyramidal, often depressed, 0.1–0.2 × 0.1–0.25 mm.

well developed, whitish, pyramidal, as high as wide to much lower than wide, 0.2–0.6 × 0.4–0.7 mm.

Eleocharis bella

Eleocharis decumbens
Phenology Fruiting spring–summer. Fruiting summer–fall.
Habitat Bare, often drying soil of stream alluvium, lake margins, wet meadows Wet fresh meadows, seeps, and lakeshores, in interior montane conifer forests and alpine zones
Elevation 200–2900 m (700–9500 ft) 700–3500 m (2300–11500 ft)
Distribution
from FNA
AZ; CA; ID; MT; NM; NV; OR; WA; Mexico (Chihuahua)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[BONAP county map]
Discussion

Eleocharis bella and E. acicularis seem to be amply distinct; putative hybrids are unknown. The occasional plants of E. bella with evident rhizomes, which include the type, are otherwise identical to plants apparently without rhizomes. Eleocharis bella is very similar to E. cancellata. There is an Illinois collection from Peoria in 1901, from the alluvial banks of the Illinois River.

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

Eleocharis decumbens is known only from Shasta and Tulare counties in California.

Although Eleocharis decumbens has long been ignored or treated as a variety of E. montevidensis, it clearly is a very distinct species, from which it differs especially in its thick rhizomes with fibrous scales and its acute floral scales.

Specimens of Eleocharis decumbens without rhizomes or achenes are easily confused with the apparently closely related E. bolanderi, which often may be distinguished by culms no more than 0.5 mm wide and spikelets with scales no more than 3 mm long. The tubercles of E. decumbens are usually well differentiated from the achenes and about as high as wide; the tubercles of E. bolanderi are often poorly developed and much lower than wide. Three collections from Jackson and Klamath counties in Oregon, lack achenes but are probably E. decumbens.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 23, p. 110. FNA vol. 23.
Parent taxa Cyperaceae > Eleocharis > subg. Scirpidium Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis
Sibling taxa
E. acicularis, E. aestuum, E. albida, E. ambigens, E. atropurpurea, E. baldwinii, 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. 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. coloradoensis, E. compressa, E. cylindrica, 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. acicularis var. bella, E. acicularis var. minima E. montevidensis var. decumbens
Name authority (Piper) Svenson: Rhodora 31: 201. (1929) C. B. Clarke: Bull. Misc. Inform., addit. ser. 8: 23. (1908)
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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