Flora of North America species comparison

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Eleocharis intermedia

Eleocharis torticulmis

Matted spikerush, mudflat spikesedge, éléocharide intermédiaire

California twisted spikerush, twist-stem spikerush
Habit Plants annual, densely tufted; rhizomes present, inconspicuous, erect or ascending, 0.5 mm thick, internodes less than 2 mm, scales disintegrating, 3 mm, membranous-translucent. Plants perennial; rhizomes 1.5–2 mm thick, scales persistent, 7–9 mm, thinly papery, sometimes fibrous; resting buds unknown; caudices present, hard, 3 mm thick.
Culms

often arching or recurved or reclining, their spikelets usually all fruiting simultaneously, long to very short in 1 tuft, subterete, 4–40 cm × 0.2–0.5 mm, soft.

erect, markedly spirally twisted, markedly obliquely contracted near spikelet, when dry often with to 6 broad, rounded ridges on each side, greatly compressed, 3–4 times as wide as thick, 20–40 cm × 1.5–2.5 mm, firm;

culm tufts not proximally bulbous.
Leaves

distal leaf sheaths persistent and evident or disintegrating (fugaceous) and not evident, proximally green or stramineous, brown, reddish, or purple, distally stramineous to green or colorless, papery to membranous, apex subacute to acuminate, sometimes with linear blade to 1 mm.

distal leaf sheaths stramineous to medium (or dark) brown, papery, apex often dark brown to reddish, broadly obtuse.
Spikelets

basal spikelets absent (often some spikelets subsessile); never proliferous, ovoid, terete, 2–10 × 1–2 mm, apex acute;

proximal scale empty or with a flower (usually in the same plant), deciduous or some persistent, amplexicaulous, similar to other scales (except apex sometimes rounded);

subproximal scale with a flower;

floral scales spiraled, 5–30, 5–6 per mm of rachilla, pale brown to colorless, often spotted brown, ovate, 1.5–2 × 1 mm, thinly membranous to translucent, midribs often green, evident to obscure, apex acute.

6–8 × 2–3 mm;

proximal scale empty, 3–4 mm, shorter than to equaling spikelet;

floral scales 8–10 per spikelet, 3.5–5 × 2 mm.
Flowers

perianth bristles 6–7, pale brown to stramineous or whitish, slender, equaling to exceeding tubercles or rarely rudimentary to less than 1/2 achene length;

spinules sparse, retrorse, sharply acute;

stamens 3 (sometimes fewer?);

anthers 0.2–0.5 mm;

styles 3-fid.

Perianth

bristles 0–5, unequal, rudimentary to equaling achene, the shorter stout, smooth or nearly so, the longer slender, densely spinulose.
Achenes

golden brown, narrowly obpyriform, proximally markedly narrowed, compressed-trigonous, angles slightly prominent, 0.9–1 × 0.6–0.75 mm, finely reticulate or pitted or papillose at 20–30X, apex usually constricted proximal to tubercle.

stramineous to medium brown, thickly trigonous, 1.75–2.75 × 1–1.25 mm;

beak 0.3–0.6 mm.
Tubercles

brown, narrowly pyramidal to linear, trigonous, 0.3–0.4 × 0.1–0.25 mm.

0.25–0.6 × 0.3–0.55 mm.
Anthers

1.8 –3 mm.
2n

= 22.

Eleocharis intermedia

Eleocharis torticulmis
Phenology Fruiting (spring–)summer–fall. Fruiting summer (Jun–Jul).
Habitat Fresh wet, often marly places along streams, lakeshores, tidal meadows, disturbed areas Fens, wet meadows, vernal ponds
Elevation 10–100 m (0–300 ft) 1100 m (3600 ft)
Distribution
from FNA
CT; IL; IN; MA; MD; ME; MI; MN; MT; NH; NJ; NY; OH; PA; TN; VA; VT; WI; WV; NB; ON; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

The flowers are mostly cleistogamous, with stigmas and stamens remaining enclosed in the floral scales except sometimes on the shortest culms. We have not seen specimens to confirm literature reports of E. intermedia from Iowa.

Eleocharis intermedia perhaps should be placed in sect. Intermediae (Svenson) Zinserling following I. Kukkonen (1990). H. K. Svenson (1929) placed it in his E. ser. Intermediae (name invalid) but later (1937, 1957) placed it in his E. subser. Truncatae (name invalid), and M. S. González-E. and P. M. Peterson (1997) placed it in E. subser. Truncatae. However, E. intermedia differs from all other members of ser. Eleocharis in its annual, tufted habit without evident, creeping rhizomes, culms varying in one tuft from long to very short, often with some spikelets subsessile, all spikelets of a tuft fruiting simultaneously, and the proximal scale often subtending a flower. It was placed in ser. Tenuissimae because of a resemblance to some other species of that series; closer observation reveals that it differs substantially in its achenes or habit from other members of ser. Tenuissimae. It rather closely resembles E. flavescens var. olivacea and E. geniculata in 8a2a. ser. Maculosae as well as small plants of species in 8a2b. ser. Ovatae.

Eleocharis macounii Fernald had been treated as a distinct species, or included within E. intermedia, E. obtusa, or E. ovata in the broad sense (including E. obtusa). P. M. Catling and S. G. Hay (1993) presented morphologic evidence suggesting that E. macounii Fernald is a hybrid between E. intermedia and E. obtusa, and named it E. ×macounii (Fernald) P. M. Catling & S. G. Hay. It is known only from the type collection from 1893 and a second collection from 1987, both from along the Gatineau River north of Ottawa in southwestern Quebec. Its habit is very similar to that of E. intermedia, from which it differs mainly in its achenes lenticular to trigonous in the same plant, the two or three angles prominent, keeled, costate, the surface smooth or very finely reticulate or pitted at 30X, and tubercles 0.2–0.5 mm wide. It produces few achenes, whereas E. intermedia and E. obtusa usually produce abundant achenes. In the protologue M. L. Fernald (1899) compared E. macounii with the Eurasian E. carniolica W. D. J. Koch. H. K. Svenson (1929, 1937) compared it with both E. intermedia and the Eurasian E. multicaulis (Smith) Smith and later (1957) placed it in synonymy under E. obtusa. Pending further research, it seems best to treat the two known collections of E. macounii as probable hybrids between E. intermedia and either E. obtusa or E. ovata; all three species are sympatric in the region where the collections of E. macounii were made (P. M. Catling and S. G. Hay 1993; B. M. H. Larson and P. M. Catling 1996).

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

Of conservation concern.

Eleocharis torticulmis is known only from the botanically rich Butterfly Valley in Plumas County.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 23, p. 96. FNA vol. 23, p. 115.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Tenuissimae Cyperaceae > Eleocharis > subg. Zinserlingia
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. 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. 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. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. vivipara, E. wolfii
Synonyms Scirpus intermedius, E. intermedia var. habereri, E. reclinata
Name authority Schultes: Mant. 2: 91. (1824) S. G. Smith: Novon 11: 250, figs. 2, 4E–I. (2001)
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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