Juncus uncialis Greene

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.

Calif., Nev., Oreg.

Flowering and fruiting spring--early summer.

Margins of vernal pools and ponds; to 1700m.

Juncus uncialis is a species of rush known by the common names twelfth rush and inch-high rush. It is native to the western United States, where it is known from wet habitat such as vernal pools. This is a petite annual herb forming dense clumps of hair-thin green stems no more than 3 or 4 centimeters high. The inflorescence is made up of a single tiny flower atop each stem. The flower has several reddish segments about 2 to 5 millimeters long wrapped around the developing fruit.

Juncus uncialis là một loài thực vật có hoa trong họ Juncaceae. Loài này được Greene mô tả khoa học đầu tiên năm 1890.