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white spikerush

horsetail spike-rush, horsetail spikesedge, jointed spike-rush, jointed spike-rush (spikesedge), jointed spikesedge, knotted spike-rush

Habit Plants perennial; rhizomes soft, longer internodes 2–4 cm, cortex loose, scales fugaceous, 6 mm, thinly membranous and translucent. Plants perennial; rhizomes 2–4 mm thick, soft to firm, longer internodes 2–8 cm, scales persistent, 7–8 mm, membranous, tubers absent.
Culms

not rooting at tips, terete, 10–40 cm, soft to firm, smooth.

terete, 50–100 cm × 5–8.4 mm, soft to firm, obscurely to clearly septate-nodulose throughout, internally hollow with complete transverse septa, closer together near the spikelet;

plants never forming filiform, flaccid culms.

Leaves

distal leaf sheaths proximally brownish or sometimes reddish, distally stramineous to green.

distal leaf sheaths persistent, membranous to thinly papery, apex acute to slightly acuminate.

Spikelets

ovoid to oblong-subcylindric, 4–12 × 2–3.5 mm, apex acute to rounded;

proximal scale empty, clasping 1/2 of culm, like floral scales;

subproximal 1 or 2 scales often empty;

floral scales 20–100, 10 per mm of rachilla, entirely stramineous or sometimes red-brown, ovate, (1.5–)2–2.5 × 1.5 mm, apex broadly rounded, entire.

not proliferous, 20–45 × 4–5(–8) mm;

rachilla joints bearing prominent winglike remnants of floral scales;

proximal scale empty, amplexicaulous, (2–)2.8–4.9 mm;

floral scales 85–160, 1–3 per mm of rachilla, stramineous to pale brown, usually with pale to dark brown submarginal band, obovate to oblong, (4.8–)5.2–7 × 3–4.4 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to obtuse.

Flowers

perianth bristles (5–)6(–8), brown, stout, the longer equaling achene or tubercle, retrorsely spinulose;

stamens 3;

anthers brown, 1 mm.

perianth bristles 3–8, stramineous to reddish, slender, vestigial to 2.5 mm, shorter than to equaling achene, smooth or obscurely retrorsely spinulose;

anthers stramineous to red-striated, 2.6–3.2 mm;

styles 2–3-fid.

Achenes

falling with scales, obovoid, angles keeled, 0.8–1 × 0.7–0.8 mm, apex with short neck.

yellowish to reddish brown, obovoid, biconvex to obscurely compressed trigonous, 1.8–2.3 × 1.4–1.9 mm, obscurely sculptured or sometimes partially smooth at 10–15X, each face with 20–40 rows of linear, transversely elongated cells, lines separating cells obscure, apex with very short neck 0.6–0.8 mm wide.

Tubercles

whitish to brown, mammillate to pyramidal, 0.2–0.3 × 0.3–0.35 mm, 1/3 or less as wide as achene.

dark brown, lamelliform, high-deltoid, 0.6–1.1 × 0.5–0.7 mm.

Eleocharis albida

Eleocharis equisetoides

Phenology Fruiting summer. Fruiting late spring–late fall.
Habitat Coastal saltmarsh edges, sloughs, beaches, dune depressions, ditches Fresh ponds, lakes, marshes, streams, ditches, cypress swamps
Elevation 0 m (0 ft) 10–500 m (0–1600 ft)
Distribution
from FNA
AL; FL; GA; LA; MD; MS; NC; NM; SC; TX; Mexico; Bermuda
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CA; CT; FL; GA; IN; LA; MA; MD; MI; MO; MS; NC; NY; RI; SC; TX; VA; WI; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

In most spikelets, the bright brown stigmas contrast strikingly with the stramineous floral scales. We have not seen vouchers for H. K. Svenson’s (1937) reports of Eleocharis albida from Virginia. The collections we have seen from Maryland are from the 1800s.

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

We have not seen voucher specimens for reports of Eleocharis equistoides from Arkansas and Tennessee. It is probably extirpated from Illinois, Missouri, and Wisconsin.

Contrary to previous decriptions, sectioning of the culm reveals that the distance between the septa near the spikelet cannot be used to distinguish the two septate species, E. equisetoides and E. interstincta, which when achenes are absent are better distinguished by the septate-nodulose distal parts of the culms of E. equisetiodes.

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

Source FNA vol. 23, p. 99. FNA vol. 23.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleocharis > ser. Albidae Cyperaceae > Eleocharis > subg. Limnochloa
Sibling taxa
E. acicularis, E. aestuum, 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
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. 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 Scirpus equisetoides, E. elliottii
Name authority Torrey: Ann. Lyceum Nat. Hist. New York. 3: 304. (1836) (Elliott) Torrey: Ann. Lyceum Nat. Hist. New York 3: 296. (1836)
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