Juncus uncialis

Herbs, annual, cespitose, 0.8--3.5 cm. Culms to 70, more than 0.2 mm diam.. Leaves to 2.2 cm, 1/2--3/4 height of plant. 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.. Flowers 3-merous, : tepals erect to recurved at maturity, greenish or tinged red, 2--4  ã 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. Capsules reddish to maroon, 3-locular, ovoid to ellipsoid, 1.8--3.2  ã 1--2.5 mm, nearly equal or shorter than the tepals. Seeds ovoid, 0.3--0.4 mm. n = 16.

Flowering and fruiting spring--early summer. Margins of vernal pools and ponds; to 1700 m; Calif., Nev., Oreg.