Ecology: Open premontane to high montane, páramo and puna; often associated with wet sites, on soil and rock. Elevation: 3100-4800 m. Distribution: Widespread in the Northern Hemisphere; in the Neotropics from Mexico, Central America, West Indies, and Andes (Venezuela to Bolivia).
Anoectangium aestivum is distinguished by the lanceolate to ovate-lanceolate leaves ca. 0.8-1/2 mm, acute apices, plane margins, percurrent costa with dorsal surface cells typically linear, papillose, ventral surface cells linear, smooth, upper laminal cells with 2–4 large, bifid, rarely simple papillae, thick-walled, rectangular basal cells. Anoectangium pflanzii Broth., collected by Pflanz in 1909 from Palca (La Paz), is a synonym.
Anoectangium aestivum se distingue por las hojas lanceoladas a ovado-lanceoladas ca. 0.8-1/2 mm, ápices agudos, márgenes planos, costa percurrente con células de la superficie dorsal típicamente lineales, papilosas, células de la superficie ventral lineares, lisas, células superiores de la lámina con 2–4 papilas grandes, bífidas, raras veces papilas simples, con paredes gruesas, células basales rectangulares. Anoectangium pflanzii Broth., colectada por Pflanz en 1909 en Palca (La Paz), es un sinónimo.