Bryol. Univ. 1:480. 1826,.
Plants in open to dense tufts, turfs, or mats, green, dark green, brownish green, light green or yellow-green, usually darker proximally, often tinged reddish brown or purple. Stems (0.2–)1–3(–4) cm. Leaves crowded, erect-patent to contorted or somewhat crisped, rarely straight when dry, lanceolate, ovate-lanceolate, or triangular-lanceolate, 0.35–2.8 mm, margins recurved to near apex or rarely plane, irregularly serrate to uneven or smooth distally, apices acute to short-acuminate or, rarely, obtuse; costa strong, sub-percurrent to excurrent, sometimes as a long, smooth awn, medial laminal cells (6.5–)8–12(–14) µm, cell walls even, usually of medium thickness, often somewhat thicker and rounded at the cell angles. Seta 1–3(–4) cm, various shades of red, orange, or yellow. Capsule oblong to long-cylindric, (1–)2–2.5(–3) mm, smooth to strongly sulcate when dry; free to united at their nodes, finely papillose to spinulose-papillose, dark red and bordered to completely pale and absent borders. Spores (10–)11–14(–17) µm.
Subspecies 4 (3 in the flora).
|1||Plants usually of various shades of green to red-brown; seta red to dark brown; capsule inclined to horizontal, oblong to cylindric, strumose, deeply sulcate when dry, usually red to red-brown to purplish, occasionally light brown||Ceratodon purpureus subsp. purpureus|
|1||Plants pale green to yellow-green to yellowish brown; seta pale yellow to yellow-orange, rarely reddish; capsule slightly inclined to erect, narrowly cylindric to cylindric, not or weakly strumose, smooth to sulcate when dry, usually pale brown to yellow (golden) -orange||> 2|
|2||Stems usually less than 0.5 cm; distal leaves relatively compact, straight to slightly twisted when dry, usually forming a comal tuft, slightly spreading when wet, 0.6-1.2 mm, margins often entire; costa long-excurrent as a smooth awn on many leaves, awns sometimes as long as leaf blade||Ceratodon purpureus subsp. conicus|
|2||Stems usually greater than 1 cm; distal leaves more open, usually crisped when dry, not forming a comal tuft, spreading when wet, 1.2-1.8 mm, margins often toothed; costa percurrent to slightly excurrent||Ceratodon purpureus subsp. stenocarpus|