Plants erect, yellowish green, in tufts. Stems 3--15 mm, radiculose. Leaves erect patent when wet, appressed when dry, 1.8--2.3 mm, lanceolate, gradually contracted, margins entire, only slightly denticulate at the extreme apex; costa filling 1/2--2/3 of the leaf base, 155 µm wide and indistinctly delimited at base, filling most parts of the leaf apex, excurrent, in transverse section with large adaxial and abaxial hyalocysts, a median band of stereids and 2--4 adaxial stereids; alar cells hyaline or brownish, often 2-stratose, slightly inflated; basal laminal cells in about 6 rows, rectangular, 15--40 ´ 10--16 µm, narrower at margins; distal laminal cells rectangular, 13--30 x 4--12 µm.

Seeping roadside rock; Calif.; Mexico, Central America; South America (n Andes).

Sporophytes have been found only once, in South America, where this species is found on soil, earth-covered rocks and bases of trees. The North American specimen differs from those from Central America by its more compact tufts and the lack of flagelliferous branches. Atractylocarpus flagellaceus was earlier regarded as a sterile, flagelliferous expression of A. stenocarpus by M. Padberg and J.-P. Frahm (1985), but was treated as separate species by J.-P. Frahm (1991). It differs from A. stenocarpus by the sterile condition, shorter leaves, narrower lamina and more distinct alar cells.