Flora of North America species comparison

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Eleocharis bella

Eleocharis fallax

beautiful spikerush, delicate spikerush, pretty spikerush

creeping spikerush, creeping spikesedge
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, mat-forming; rhizomes evident, long, 1–2 mm thick, firm, cortex persistent, longer internodes 5–10(–20) mm, scales sometimes fugaceous, 5–7 mm, papery (to membranous), sometimes fibrous.
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 to 12 blunt ridges when dry, 30–75 cm × 0.5–1.5 mm, firm, internally spongy.
Leaves

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

distal leaf sheaths persistent, not splitting, proximally dark red, distally stramineous or green, papery to membranous, apex dark redbrown, obtuse, not callose, tooth rarely present on some culms, 0.2 mm.
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 or subspheric, 5–12 × 2–3(–4) mm, apex acute to obtuse;

proximal scale amplexicaulous, entire;

subproximal scale with flower;

floral scales deciduous, often spreading in fruit, 10–35, 3 per mm of rachilla, red-brown to blackish brown, midrib regions sometimes green, ovate, 2.5–3 × 1.7 mm, apex entire, obtuse to acute, often carinate in distal part of spikelet.
Flowers

perianth bristles absent;

anthers 0.3–0.5 mm.

perianth bristles 1–5, brown, stout, very unequal, rudimentary to equaling achene;

stamens unknown [absent from specimens];

styles 3-fid or some 2-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.

not persistent, dark yellow or medium brown, obovoid to obpyriform, compressed trigonous, or some thickly biconvex, angles evident, 1.1–1.5 × 0.95–1.25 mm, apex rounded, neck very short (to absent), finely rugulose at 10–20X, 20 or more horizontal ridges in vertical series, finely cancellate at 20–30X.
Tubercles

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

whitish to brown, pyramidal, not depressed, as high as wide, 0.3–0.5 × 0.4–0.6 mm.
2n

= 42.

Eleocharis bella

Eleocharis fallax
Phenology Fruiting spring–summer. Fruiting late summer.
Habitat Bare, often drying soil of stream alluvium, lake margins, wet meadows Coastal, fresh to brackish pond and lakeshores, marsh
Elevation 200–2900 m (700–9500 ft) 0–10 m (0–0 ft)
Distribution
from FNA
AZ; CA; ID; MT; NM; NV; OR; WA; Mexico (Chihuahua)
[WildflowerSearch map]
[BONAP county map]
from FNA
MA; NJ; NS
[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.)

Of conservation concern.

The taxonomic status of Eleocharis fallax is problematic. I have seen only the type, from 1919 from a pond on Cape Cod, Massachusetts; a specimen from 1955 from Inverness County, Nova Scotia; and a specimen from the Passaic River marshes in New Jersey. It is reportedly extirpated from the type locality (M. L. Fernald 1950). Another specimen from Cape Cod is typical of E. fallax except for some lenticular achenes. I have not seen a voucher for the material, reportedly collected by H. K. Svenson from a brackish marsh on Plum Island, Essex County, Massachusetts, from which S.-O. Strandhede (1967) counted the chromosome number. It seems possible that these collections are of hybrid origin from E. elliptica and either E. erythropoda or E. uniglumis var. halophila (M. L. Fernald 1950). The plants are similar to E. erythropoda except for their trigonous, rougher achenes and sometimes fibrous rhizome scales, which suggests introgression from E. elliptica. Because some specimens of E. ambigens, including the type, have mixtures of lenticular and trigonous achenes, E. fallax is often treated as conspecific with E. ambigens, from which it differs only in its 3-fid styles, trigonous, more rugulose achenes, and higher tubercles. It seems best to recognize E. fallax as a species pending further research because the plants bear many, apparently normal achenes and are not exactly intermediate between their putative parents, and to avoid using a name for the widespread E. ambigens that may apply only to rare hybrids.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 23, p. 110. FNA vol. 23, p. 78.
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. decumbens, E. diandra, E. elliptica, E. elongata, E. engelmannii, E. equisetoides, E. erythropoda, 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
Name authority (Piper) Svenson: Rhodora 31: 201. (1929) Weatherby: Rhodora 24: 23. (1922)
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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