Plants small to medium-sized, pale to dark green to golden brown. Stems 1-3 cm, reclining to suberect, weakly complanate-foliate, pinnate to irregularly branched. Leaves usually falcate, sometimes strongly so, long-ovate or ovate-lanceolate, gradually narrowed to apex; margins subentire to distinctly toothed distally; alar cells many and subquadrate or few and quadrate, . Branch leaves 1-2 × 0.2-0.6 mm, sometimes smaller or larger.
Plants medium-sized to large (rarely slender). Branches flattened. Leaves falcate-secund, gradually narrowed to a long, slender acumen.
On soil, rock and tree-trunks at roadsides or in forests of Abies, Pinus, Quercus, 2600-4100 m alt.; Chihuahua, Coahuila, Distrito Federal, Durango! Hidalgo, Mexico, Nuevo Leon, Veracruz.—Mexico; widely distributed around the world except in tropical areas (very common in Europe but not common in North America and Mexico).