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three-angle spikerush, three-angle spikesedge

tidal spikerush, tidal spikesedge

Habit Plants perennial, mat-forming; rhizomes evident, fairly long, 1.5–3 mm thick, hard, cortex persistent, longer internodes 1.5–3 mm, scales disintegrating to fibers, 4–5 mm, papery.
Culms

terete, often with 8–12 blunt ridges when dry, 20–55 cm × 0.3–1.3 mm, soft to hard.

often spreading or declining, 3–30 cm × 0.5–1 mm.

Leaves

distal leaf sheaths persistent, rarely splitting, proximally red to stramineous, distally green to reddish, papery, apex often dark reddish, subtruncate to obtuse, not callose, tooth present on some or all culms of plant, to 0.5 mm.

apex of distal leaf sheath obtuse, tooth to 0.2(–0.5) mm.

Spikelets

cylindric to ovoid, 5–20 × 2–3 mm, apex rounded to subacute;

proximal scale amplexicaulous, apex entire;

subproximal scale empty;

floral scales appressed in fruit, 20–200+, 10 per mm of rachilla, dark brown, midrib regions often stramineous or greenish, oblong, 1.7–2.5 × 1 mm, apex entire, broadly rounded, usually recurved, mostly carinate.

ellipsoid to ovoid, 3–10 × 2–4 mm, apex blunt to subacute;

floral scales 10–100+, 10 per mm of rachilla, colorless to pale brownish except for green midrib, 1.5–2 × 1 mm, midribs not keeled, apex rounded.

Flowers

perianth bristles absent;

stamens 3;

anthers dark yellow, 1–1.5 mm;

styles 3-fid.

perianth bristles absent or 2–4, stramineous or whitish, shorter than to nearly 1/2 achene, very slender, without spinules;

stamens 2(–3);

anthers 0.3–0.5 mm;

styles 2-fid or some 3-fid.

Achenes

falling with scales, medium to dark brown, obovoid to obpyriform, with short neck, thickly trigonous, angles prominent (keeled), 0.7–0.9 × 0.4–0.6 mm, obscurely to clearly rugulose at 10–20X with more than 20 horizontal ridges in vertical series and/or minutely cancellate at 20–30X.

0.75–1 × 0.6–0.8 mm.

Tubercles

brown, rudimentary, mostly apiculate, sometimes pyramidal, 0.05–0.15 × 0.15–0.2 mm.

deltoid, 0.2–0.3 × 0.35–0.45(–0.55) mm, 1/2–3/4as high as wide, 1/4–1/3 as high and 1/2–2/3(–4/5) as wide as achene.

Eleocharis tricostata

Eleocharis aestuum

Phenology Fruiting late spring–summer. Fruiting summer–fall (Jul–Oct).
Habitat Wet sandy or peaty depressions, pond margins, pine barrens, savannas, mostly coastal plains Fresh tidal river shores
Elevation 10–200 m (0–700 ft) 0–10 m (0–0 ft)
Distribution
from FNA
AL; FL; GA; MA; MI; NC; NJ; NY; SC; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; DE; MA; ME; NJ; NY; PA
[BONAP county map]
Discussion

I have not seen specimens to verify reports of Eleocharis tricostata from Louisiana. In the absence of rhizomes and achenes, E. tricostata is easily mistaken for E. montevidensis.

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

Eleocharis aestuum is very similar to E. diandra and E. ovata; E. diandra differs from E. aestuum in its lower tubercles, brown floral scales, and absence of perianth bristles; E. ovata differs as given in the key to species. D. M. Hines (1975) described E. aestuum using the epithet “palidostachys” [ined.]. Specimens from shores of the Lake-of-the-Woods in Minnesota, and a reservoir and farm in Hardin and Fayette counties, Tennessee, may be referable to E. aestuum. The only recent records of E. aestuum are from the Androscoggin and Kennebec rivers in Maine and the Hudson River in New York (A. Haines 2001).

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

Source FNA vol. 23, p. 88. FNA vol. 23, p. 104.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Eleocharis Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae
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. 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. tuberculosa, E. uniglumis, E. vivipara, E. wolfii
E. acicularis, 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. torticulmis, E. tortilis, E. tricostata, E. tuberculosa, E. uniglumis, E. vivipara, E. wolfii
Name authority Torrey: Ann. Lyceum Nat. Hist. New York. 3: 310. (1836) Hines ex A. Haines: Novon 11: 45. (2001)
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