Herbs, perennial, tufted, 1--4 dm. Rhizomes densely branching. Culms few to many, erect to drooping. Cataphylls 2--4. Leaves basal and cauline, 2--4; auricles deeply lacerate, to 4 mm, membranous; blade dark green, flat to slightly channeled, 5--12 cm x 0.5--1 mm, margins finely serrulate. Inflorescences 1--3(--4)-flowered; primary bract usually exceeding inflorescence. Flowers: bracteoles 2, usually lacerate; tepals brownish, widely lanceolate, 2.1--3 mm; inner series slightly shorter, apex acute; stamens 6, filaments 0.3--0.7 mm, anthers 1.2--1.5 mm; stigma 1.5--3 mm. Capsules brown, ellipsoid, 2.2--3.5 x 1.3--1.7 mm, longer than tepals. Seeds brown, obliquely ovoid, 0.89--1.35 mm, not tailed. 2n = 40. Flowering and fruiting late spring--early summer. Mostly in crevices of granitic (schistose) cliffs or rubble slopes in the higher regions of the Appalachians; 20--2000 m; Greenland; N.B., Nfld. and Labr., N.S., Que.; Maine, N.H., N.Y., N.C., Tenn., Vt., Va.; Europe; n Asia.
Stems densely cespitose from a short rhizome, 5-30 cm up to the infl, surrounded at base by crowded sheaths ca 3 cm, naked for most of their length, and bearing toward the summit 2 or 3 filiform, minutely serrulate lvs 4-10 cm and 1 or sometimes 2 simple infls of 1-4 fls, the fls prophyllate, with lacerate bracteoles; basal sheaths with fimbriate-lacerate auricles and a short bristle-tip; tep lanceolate or lance-ovate, brown, the sep acuminate or aristate, mostly 3-4 mm, the pet acute or acuminate, slightly shorter; anthers 6, ca twice as long as the filaments; fr trilocular, 2.5-3.5 mm, broadly obovoid, with a slender beak ca 1 mm; seeds few, irregularly polyhedral, 0.6-1.3 mm; 2n=30. Rock crevices and alpine meadows; Europe and ne. Amer., s. in the mts. to Va. and N.C. Plants from N.Y. southward mostly have relatively large fls for the sp., with only 1 or 2 fls per infl, and have been segregated as ssp. carolinianus H宥t-Ahti (var. monanthos, misapplied). More northern plants in e. N. Amer. mostly have 2-4 fls per infl and pass as typical J. trifidus.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.