Plants pale green to green dorsally with purple ascending margins and dark purple undersides, edges tending to curl upward exposing the dark underside when dry; branching dichotomous, seldom with intercalary branches. Thalli 10 25 ´ 4 10 mm; epidermis faintly areolate, cells 50 ´ 30 µm with thin walls, trigones small or lacking, oil cells few, scattered; air pores surrounded by 2 3 tiers of 6 7 cells with slightly thickened radial walls; ventral scales purplish with few oil cells; appendages 1 3, hyaline, triangular acuminate. Sexual condition dioecious; separate male plants often intermingled with female plants; androecia dorsal, forming thick, distinct ovate or elongate patches, sometimes with subulate scales around the margins; gynoecia terminal on thalli, stalks slightly purplish, 1 3 cm with pale, long, fine, hairlike scales at apices, none at bases; carpocephala pale green, 4 5 mm across, hemispheric, becoming umbonate with age, distinctly lobed with 3 4( 5) lobes directed horizontally outward; pseudoperianths conical, white with 12 or more segments, connate at apices. Sporophyte capsules yellowish; spores yellow, 100 120 µm; elaters yellowish, 1 2 spiral, 250 300 µm.

Capsules mature Jan.--May. Soil of shaded banks in rather dry areas; Ariz. (Gila Co.), Calif., sw Oreg.; Mexico (Baja California Norte).

This is the only dioecious species in the flora. The female receptacles are large for the size of the plant and the pseudoperianths are directed outward horizontally rather than downward. The pale color of the carpocephala is in sharp contrast with the inrolled thalli covering the green upper surface exposing the dark purple underside.