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small-head rush

Cooper's rush

Habit Herbs, perennial, cespitose, 2–7 dm. Herbs, perennial, robust, tufted, 4–10 dm.
Rhizomes

short.

Culms

erect, 1–4 mm diam., smooth.

terete, 1.5–2.5 mm diam.

Cataphylls

1–2, straw-colored to pink, apex acute.

several, reddish brown, often apiculate.

Leaves

basal 1–3, cauline 1–2;

auricles 0.6–1.5 mm, apex rounded, scarious;

blade terete to compressed, 0.2–12 cm × 0.5–2 mm.

basal, 1–2;

auricles essentially absent;

blade terete, 10–40 dcm, shorter than culm.

Inflorescences

panicles of 5–80 heads, 5–25 cm, branches ascending;

primary bract erect;

heads 2–6-flowered, ellipsoid to obovoid, 2–5 mm diam.

glomerules 3–12, each with (1–)2–5 flowers, open, branches unequal, 3–12 cm, primary bract terete or slightly compressed, shorter to longer than inflorescence.

Flowers

tepals green to light brown, lanceolate;

outer tepals 1.8–2.5 mm, apex obtuse to nearly acute;

inner tepals 2–2.8 mm, apex obtuse to nearly acute;

stamens 3 or 6, anthers 1/2 filament length.

tepals straw-colored to pale green, ovate-lanceolate, 4–5 mm, apex acuminate or setaceous;

inner series elliptic, nearly equal, margins wide, scarious, apiculate;

stamens 6, filaments 1 mm, anthers 1.5–2 mm;

style 1 mm.

Capsules

exserted, chestnut to dark brown, imperfectly 3-locular, obconic, 2.4–3.8 mm, apex acute proximal to beak, valves separating at dehiscence.

tan to light reddish brown, 3-locular, ellipsoid, 3.7–4.5 ×1.6–2 mm, mostly shorter than or nearly equal to perianth.

Seeds

ellipsoid to fusiform, 0.8–1.2 mm, tailed;

body covered with whitish translucent veil.

dark amber, obovoid, body 0.7–1 mm, tails 0.1–0.5 mm.

2n

= 80.

Juncus brachycephalus

Juncus cooperi

Phenology Fruiting summer–early fall. Flowering and fruiting spring–summer.
Habitat Calcareous marshes, wet meadows, and wetland shores Saline flats and meadows or edges of salt marshes
Elevation 100–200 m (300–700 ft) below 600 m (below 2000 ft)
Distribution
from FNA
AL; CO; CT; GA; IL; IN; MA; ME; MI; MN; NC; ND; NH; NJ; NY; OH; OK; PA; TN; VA; VT; WI; WV; NB; NS; ON; QC;
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NV; UT; Mexico
[BONAP county map]
Source FNA vol. 22. FNA vol. 22.
Parent taxa Juncaceae > Juncus > subg. Septati Juncaceae > Juncus > subg. Juncus
Sibling taxa
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
Synonyms J. canadensis var. brachycephalus
Name authority (Engelmann) Buchenau: Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 12: 268. (1890) Engelmann
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