Juncus subtilis

Herbs, perennial, emergent, rhizomatous (forming mats to 5 dm), 0.5--1 dm. Rhizomes 1 mm diam., nodes not swollen. Culms repent, floating or submersed, usually profusely branched, terete, 0.5--1 mm diam. Cataphylls absent. Leaves: basal 1--5, cauline 1--4, small fascicles of short capillary leaves often on rhizomes and stems; auricles 0.1--0.8 mm, apex acute, membranaceous; blade terete, 1.6--3 cm x 0.1--0.3 mm. Inflorescences cymes, flowers 1--3 at 1--2 nodes, 1--4 cm, branches spreading to erect. Flowers: tepals reddish, oblong; outer tepals 1.8--2.8 mm, obtuse; inner tepals 2.2--4.4 mm, obtuse; stamens 6, anthers 3/4 to equal filament length. Capsules exserted, chestnut brown, 1-locular, ovoid to narrowly ovoid, 2.4--5 mm, apex acute proximal to beak, valves separating at dehiscence. Seeds ovoid, 0.3--0.5 mm, not tailed; body clear yellow-brown. 2n = 40.

Fruiting late summer--early fall. Muddy, sandy or gravelly shores, fens in decomposed peat, fine muds rich in humus, and submersed in brackish pools; 0--200 m; Greenland; N.B., Nfld. and Labr., Ont., Que.; Maine.

Flowers are rarely replaced by bulbils. Most Greenland collections are sterile.

Stems very slender, 0.5-5 dm, floating or prostrate and repent, mat- forming and scarcely arising above the substrate, bearing at many nodes small fascicles of short capillary lvs; infl 1-4 dm, simple or nearly so, usually with fls at only 1 or 2 nodes, often many of them replaced by subulate bulbils; tep 2.2-2.8 mm; pet 2.5-4.4 mm; anthers 6, usually shorter than the filaments; fr 3-5 mm; otherwise much like no. 35 [Juncus pelocarpus E. Mey]. Muddy shores; Nf. to Me. and w. Que.; Greenl.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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