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inch high dwarf rush, inch-high rush, twelfth rush

Mertens' rush

Habit Herbs, annual, cespitose, 0.8–3.5 cm. Herbs, perennial, rhizomatous to cespitose, 0.5–4 dm.
Rhizomes

1–2 mm diam., not swollen.

Culms

to 70, more than 0.2 mm diam..

erect, terete, 1–3 mm diam., smooth.

Cataphylls

0–1, straw-colored to chestnut brown, apex acute.

Leaves

to 2.2 cm, 1/2–3/4 height of plant.

basal 1–2, cauline 0–1;

auricles 1–1.2 mm, apex rounded to acute, membranaceous or scarious;

blade green to straw-colored, terete, 3–15 cm × 0.3–0.6 mm.

Inflorescences

terminal solitary flowers;

bracts subtending inflorescence 1, widely truncate, enwrapping culm, inconspicuous, 0.25–0.9 mm, membranous, apex widely truncate, completely sheathing culm..

terminal single head (rarely cluster of 2 heads), 0.5–1.6 cm;

primary bract erect;

heads 12–60-flowered, spheric (to hemispheric), 4.5–15 mm diam.

Flowers

3-merous, : tepals erect to recurved at maturity, greenish or tinged red, 2–4 × 0.6–0.9 mm;

outer and inner series nearly equal, apex acutish;

stamens usually 3, filaments 0.9–1.6 mm, anthers 0.3–0.4 mm, 1/3 length of filaments;

style 0.1–0.3 mm, stigma 0.4–1.3 mm.

tepals dark purplish brown to black, lanceolate to lance-ovate, apex acute, mucro subulate;

outer tepals 2.4–4.9 mm;

inner tepals 2.3–4.3 mm;

stamens 6, anthers 1/4 to equal filament length.

Capsules

reddish to maroon, 3-locular, ovoid to ellipsoid, 1.8–3.2 × 1–2.5 mm, nearly equal or shorter than the tepals.

included or slightly exserted, chestnut brown, 1-locular, obovoid, 1.9–3.5 mm, apex obtuse or rounded, valves separating at dehiscence, fertile throughout or only proximal to middle.

Seeds

ovoid, 0.3–0.4 mm.

ellipsoid, 0.4–0.5 mm, not tailed;

body clear yellow-brown.

n

= 16.

2n

= 40.

Juncus uncialis

Juncus mertensianus

Phenology Flowering and fruiting spring–early summer. Fruiting mid summer–fall.
Habitat Margins of vernal pools and ponds Montane to alpine meadows, stream banks, lake margins, and conifer woods
Elevation 0–1700 m (0–5600 ft) (400–)1900–3300 m ((1300–)6200–10800 ft)
Distribution
from FNA
CA; NV; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; NT; SK; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Populations from southern California with brown tepals, anthers equaling filaments, and rounded to acute, translucent auricles have been separated as Juncus duranii; the typical form is so highly variable, however, that it can easily accommodate this local form. This species passes into Juncus nevadensis and has often been combined with that species (F. J. Hermann 1964). The two species can generally be separated, and we are following those treatments (F. J. Hermann 1975; A. Cronquist et al. 1972+, vol. 6).

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

Source FNA vol. 22. FNA vol. 22, p. 252.
Parent taxa Juncaceae > Juncus > subg. Graminifolii Juncaceae > Juncus > subg. Septati
Sibling taxa
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. 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. 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. 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. 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. duranii, J. mertensianus var. duranii, J. mertensianus var. filifolius, J. slwookoorum
Name authority Greene: Pittonia 2: 105. (1890) Bongard: Mém. Acad. Imp. Sci. St.-Pétersbourg, Sér. 6, Sci. Math. 2: 167. (1833)
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