Chestnut Rush

In southern Alaska some plants with several many-flowered heads and capsules about double the length of the perianth have been referred to the Asian Juncus castaneus subsp. leucochlamys. The distinction, however, seems dubious without further investigation.

Herbs, perennial, strongly rhizomatous, 1--4 dm. Culms solitary, 1--2 mm diam. Cataphylls 1--2. Leaves partially cauline, 3--5, auricles absent distally, rounded proximally; blade channeled, to 20 cm, reduced distally. Inflorescences glomerules, 1--3(--5), each with 2--10 flowers; peduncles 0.4--1.5 cm; primary bracts somewhat inflated, usually surpassing inflorescence. Flowers: bracteoles absent; tepals brown or occasionally paler, lanceolate, 4.5--6.6 mm, apex acute to obtuse; inner series slightly shorter; stamens 6, filaments 2.5--3.5 mm, anthers 0.6--1.3 mm; style 1--1.3 mm. Capsules chestnut brown, 3-locular, narrowly oblong, 6.5--8.5 x 1.8--2.3 mm. Seeds pale yellow, fusiform, body 0.6--0.7 mm, tails 0.8--1.1 mm. 2n = 60, 90, 120.

Plants perennial, 15--40 cm tall. Rhizome of long, subterranean runners. Stem usually solitary, terete, 2--3.5 mm in diam. Cataphylls few. Basal leaves 2--4, cauline leaf absent or 1; leaf sheath auricles absent; leaf blade flat, 6--25 cm × 3--6 mm, margin usually involute. Inflorescences with involucral bracts 1 or 2, leaflike, usually longer than inflorescence; heads 2--8, hemispheric, 7--9 mm in diam. at anthesis, 4--10-flowered; bracts 2 or 3, lanceolate, usually shorter than flowers. Pedicels ca. 2 mm. Perianth segments dark brown to chestnut brown, narrowly ovate to lanceolate, 4--5 mm, unequal with outer ones slightly longer than inner, apex acuminate. Stamens 6; filaments ca. 2 mm; anthers ca. 1 mm. Style 1--1.5 mm; stigmas 2--3 mm. Capsule trigonous ellipsoid, 6--7 mm, 3-septate, base lighter colored, apex reddish brown, tapered to an acute tip. Seeds ca. 1 mm, both ends appendaged; appendages white, ca. 1 mm. Fl. Jul--Aug, fr. Aug--Sep. 2 n = 40, 60.

Greenland; Alta., B.C., Man., Nfld. and Labr. (Labr.), N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Colo., Mont., Nev., N.Mex., Utah, Wyo.; Europe; Asia.

Gansu, Hebei, Jilin, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Yunnan [Russia (Siberia); Europe, North America].

Flowering and fruiting late spring--summer.

Tundra, subalpine and alpine bogs and meadows, and along streams in gravelly or clayey soils; 10--3700m.

Wet meadows or swamps in mountainous areas; 2100--3100 m.

Juncus castaneus var. pallidus (Hooker ex Buchenau) B. Boivin; J. castaneus subsp. leucochlamys (N. W. Zinger. ex V. I. Kreczetowicz) Hultén; J. leucochlamys N. W. Zinger ex V. I. Kreczetowicz