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, ovatelanceolate, 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, subpercurrent 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|