Bryum procerum Schimp. ex Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 119. 1872.
Rhodobryum procerum (Schimp. ex Besch.) Par., Index Bryol. 1119. 1898. Protologue: Mexico. Orizaba, in pinetis (Liebmann); in sylva San Nicolas, prope Mejico (Bourg. sept. 1865).
Bryum mangini[i] Card., Rev. Bryol. 36: 115. 1909. Protologue: Mexico. Mexique, sans indication de localité (Diguet; herb Museum [Paris]).
Plants robust, green to yellowish green in loose tufts to (3–)7–14(–36) cm high; rhizoids reddish brown, papillose, densely clothing stems. Leaves 6–12 x 4–6 mm, erect to erect-spreading, laxly contorted, evenly and well‑spaced along stems, at times erect‑imbricate and spirally contorted when dry, ovate‑lanceolate; apices acuminate; margins recurved below, plane above, bordered by 4–5 rows of long, narrow, thick-walled cells, sharply serrate in upper half, the teeth single or double, decurrent at base; costae shortly excurrent, in cross section with several layers of enlarged ventral cells, median guide cells and a weakly developed cluster of dorsal stereids; upper cells rhomboidal to long-hexagonal, firm‑walled, often porose, 60–110 x 20–30 μm, basal cells long‑rectangular, 160–140 x 30 μm, alar cells shorter and broader, otherwise weakly differentiated. Dioicous. Setae 1–5 per perichaetium, 30–50 mm long, dark-red. Capsules 4–7 mm long, cylindrical, inclined to pendent, weakly striate at base; opercula 1 mm long, conic-apiculate; peristome perfect, exostome teeth red-yellow, densely and finely papillose below, more coarsely papillose above, strongly trabeculate at back, endostome yellowish hyaline, lightly papillose, basal membrane to ½–_ of exostome teeth length, segments well-developed, broadly perforate, cilia 2–3, appendiculate. Spores 10–16 μm, lightly papillose. Calyptra not seen.