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purple spike-rush

pale spike-rush, wrinkle-sheath spike-rush, yellow spikerush, yellow spikesedge

Habit Plants tufted, without creeping rhizomes. Plants with creeping rhizomes 0.5–1 mm thick.
Culms

2–12(–19) cm × 0.2–0.4 mm.

3–42 cm × 0.3–0.6 mm.

Leaves

distal leaf sheaths firm, distally tightly sheathing, apex acute.

distal leaf sheaths often disintegrating, thinly membranous-translucent, inflated distally, often wrinkled, apex blunt.

Spikelets

ovoid to ellipsoid, 2–6(–8) × 1–2.5 mm, apex acute;

proximal scale with or without flower, not amplexicaulous;

floral scales to 100, 15–19 per mm of rachilla, often loosely appressed, dark red-brown to stramineous, ovate to elliptic, 0.6–1.3 × 0.3–0.7 mm, membranous, apex rounded to acute.

ellipsoid, 1.5–9 × 1–3.5 mm, apex acute to acuminate;

proximal scale without flower, not amplexicaulous;

floral scales to 65, 5–7 per mm of rachilla, loosely appressed to appressed, elliptic, 1–3 × 0.4–1.6 mm, membranous, apex acute.

Flowers

perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous;

styles 2-fid.

perianth bristles (0–)5–8, typically 7, white to stramineous, spinules dense to few;

styles 2-fid, rarely 3-fid.

Achenes

black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X.

stramineous to green or dark brown, biconvex, rarely trigonous, obovoid to obpryiform, 0.4–1.1 × 0.3–0.8 mm, very finely reticulate at 40X.

Tubercles

stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute.

whitish to stramineous or green, 0.2–0.7 × 0.2–0.4 mm, apex acute to acuminate.

2n

= 20.

Eleocharis atropurpurea

Eleocharis flavescens

Phenology Fruiting summer–fall (Jun–Sep).
Habitat Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields
Elevation 0–1800 m (0–5900 ft)
Distribution
from FNA
AL; CA; FL; GA; IA; KS; LA; MI; MO; NC; NE; NM; OK; SC; TX; WA; BC; Mexico; Central America; South America; West Indies; Europe (naturalized); Asia; Africa; Pacific Islands
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; AZ; CA; CT; DE; FL; GA; ID; IL; IN; LA; MA; MD; ME; MI; MN; MS; MT; NC; NH; NJ; NY; OH; PA; RI; SC; TX; UT; VA; VT; WI; WY; NB; NS; ON; QC; South America; temperate North America; West Indies
[WildflowerSearch map]
[BONAP county map]
Discussion

Eleocharis atropurpurea has been reported from Colorado, Montana, and Virginia; I have not seen voucher specimens.

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

Varieties 2 (2 in the flora).

The varieties of Eleocharis flavescens are difficult to delimit, especially in the south, and identifications of some specimens to variety are problematic.

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

Key
1. Achenes red-brown to dark brown when ripe, 0.4–0.8(–1.1) × 0.3–0.6 mm, apex rarely highly constricted proximal to tubercle; flowers with perianth bristles typically shorter than to as long as achene.
var. flavescens
1. Achenes green to golden-brown, 0.5–1.1 × 0.4–0.8 mm, often highly constricted proximal to tubercle; flowers with perianth bristles typically longer than achene.
var. olivacea
Source FNA vol. 23, p. 102. FNA vol. 23, p. 100.
Parent taxa Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Maculosae
Sibling taxa
E. acicularis, E. aestuum, E. albida, E. ambigens, 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. equisetoides, E. erythropoda, E. fallax, 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. flavescens var. flavescens, E. flavescens var. olivacea
Synonyms Scirpus atropurpureus Scirpus flavescens
Name authority (Retzius) J. Presl & C. Presl: in C. B. Presl, Reliq. Haenk. 1: 196. (1828) (Poiret) Urban: Symb. Antill. 4: 116. (1903)
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