Flora of North America species comparison

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Eleocharis bella

Eleocharis subg. Scirpidium

beautiful spikerush, delicate spikerush, pretty 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 annual or perennial, very rarely with spikelets proliferating, culms never rooting at tips (spikelets very rarely proliferating in Eleocharis reverchonii).
Rhizomes

present or absent, creeping.
Culms

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

1–40 cm × 0.2–1.2 mm, spongy, transverse septa incomplete.
Leaves

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

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 to subcylindric, terete, much wider than their culms, 2–9 mm;

rachilla with proximal internodes as long and as thick as internodes in middle of spikelet;

proximal scale subtending a flower;

floral scales ca. 4–30 per spikelet, spiraled, 1–3.5 mm, with 1 vein or fewer than 10 widely spaced longitudinal veins, membranous.
Flowers

perianth bristles absent;

anthers 0.3–0.5 mm.

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.

trigonous to nearly terete, 0.5–1.1 mm, with 9–13 longitudinal rows of fine horizontal ridges (trabeculae) between much more prominent longitudinal ridges and achene angles.
Tubercles

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

distinct from achene in color, texture and form, not dorsoventrally greatly compressed.
Tubers

and bulbs (resting buds) absent, or resting buds sometimes present in E. acicularis.

Eleocharis bella

Eleocharis subg. Scirpidium
Phenology Fruiting spring–summer.
Habitat Bare, often drying soil of stream alluvium, lake margins, wet meadows
Elevation 200–2900 m (700–9500 ft)
Distribution
from FNA
AZ; CA; ID; MT; NM; NV; OR; WA; Mexico (Chihuahua)
[WildflowerSearch map]
[BONAP county map]
North America to South America; West Indies; Eurasia; Hawaii; Australia (probably introduced)
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.)

Species ca. 12 (7 in the flora).

The three achene angles are very similar to the longitudinal ridges. Plants of subg. Scirpidium without achenes are easily mistaken for plants of 8a3. Eleocharis subg. Eleocharis sect. Parvulae, which may be distinguished by the absence of a flower in the axil of the proximal scale of the spikelet.

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

Key to the species of Eleocharis subg. Scirpidium

1. Culms distinctly compressed, to 1.2 mm wide, each side with 1 to few sharp ridges or 1 side smooth, margins usually––and ridges often––minutely serrulate at 10–30X; spikelet scales (2.2–)2.7–3.2 mm.
E. wolfii
1. Culms not or slightly compressed, or if distinctly compressed then each side with 3–6 blunt ridges, to 0.5(–0.7) mm wide, margins and ridges smooth; spikelet scales 0.8–2.5(–3.5) mm.
→ 2
2. Floral scales 0.8–2 mm, apex narrowly acute to acuminate, mostly slightly recurved; anthers 0.2–0.5 mm; culms 1–7 cm, mostly densely tufted; rhizomes seldom evident.
→ 3
2. Floral scales 1.5–2.5 mm, apex rounded to acute, not recurved; anthers 0.3–1.5 mm; culms 1–45 cm; rhizomes mostly evident.
→ 5
3. Achenes 0.4 mm, obpyriform; anthers 0.7–1.2 mm; floral scales lanceolate, folded lengthwise.
E. brachycarpa
3. Achenes 0.5–0.75 mm, obovoid, rarely obpyriform; anthers 0.2–0.5 mm; floral scales ovate to lanceolate, not folded lengthwise.
→ 4
4. Achenes broadly obovoid to obpyriform, 0.5–0.6 mm, trabeculae 15–20; anthers 0.2–0.3 mm.
E. cancellata
4. Achenes obovoid, (0.55–)0.65–0.75 mm, trabeculae 20–30; anthers (0.2–)0.3– 0.5 mm.
E. bella
5. Anthers 0.3–0.5 mm; culms very spongy, without prominent ridges or angles, 1–12 cm.
E. radicans
5. Anthers 0.5–1.5 mm; culms firm to flaccid, not very spongy, often prominently ridged or angled, 1–45 cm.
→ 6
6. Achenes 0.5–0.7 mm, trabeculae 20–30; scales 1.5–1.7 mm; culms 0.15–0.3 mm wide.
E. reverchonii
6. Achenes 0.7–1.1 mm, trabeculae 30–60; scales 1.5–2.5(–3.5) mm; culms 0.2– 0.5(–0.7) mm wide.
E. acicularis
Source FNA vol. 23, p. 110. FNA vol. 23.
Parent taxa Cyperaceae > Eleocharis > subg. Scirpidium Cyperaceae > 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
Subordinate taxa
E. acicularis, E. bella, E. brachycarpa, E. cancellata, E. radicans, E. reverchonii, E. wolfii
Synonyms E. acicularis var. bella, E. acicularis var. minima subg. Scirpidium, E. series Aciculares
Name authority (Piper) Svenson: Rhodora 31: 201. (1929) (Nees) Kukkonen: Ann. Bot. Fenn. 27: 114. (1990)
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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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