6. Campyliadelphus (Kindberg) R. S. Chopra, Taxon. Indian Mosses. 442. 1975. • [Genus Campylium and Greek adelphos, brother, alluding to similarity].
Hypnum sect. Campyliadelphus Kindberg, Bih. Kongl. Svenska Vetensk.-Akad. Handl. 7(9): 16. 1883
Plants small to medium-sized, green, yellow-green, or brownish. Stems irregularly branched to pinnate; hyalodermis absent, central strand narrow; paraphyllia absent; rhizoids or rhizoid initials on stem or abaxial costa insertion, rarely forming tomentum, slightly or strongly branched, smooth; axillary hair distal cells 1-4, hyaline. Stem leaves almost erect to spreading, straight or falcate [± recurved], rounded-triangular or ovate to broadly ovate, not plicate, 1 mm; base decurrent; margins plane, or slightly recurved basally, partly entire, partly sinuate or weakly and often obtusely denticulate, limbidia absent; apex long-acuminate, ; costa single to (2/5 -)1/2 -4/5 leaf length, occasionally double and short, ; alar cells differentiated, transversely rectangular, rectangular, short-rectangular, or short-linear, slightly inflated, , region distinctly or indistinctly delimited, quadrate, ovate, or broadly ovate; medial laminal cells rectangular or linear; ; marginal cells 1-stratose. Sexual condition dioicous. Capsule horizontal, cylindric or short-cylindric, curved; peristome perfect; exostome margins dentate or slightly dentate distally; endostome cilia nodose or partially appendiculate. Spores 8-21 µm.
Species 3 (1 in the flora): North America, Mexico, West Indies, Central America, n South America, Eurasia, Africa.
Campyliadelphus grows on wet or periodically moist calcareous substrates. Campyliadelphus species are similar to Drepanocladus arcticus, D. cardotii, D. polygamus, and species of Campylium and Campylophyllum, in that their leaves are at least partly recurved or squarrose, and the leaf acumen is furrowed. The species of Drepanocladus mentioned above and those of Campylium consist of plants that are mostly larger than those of Campyliadelphus, have only foliose pseudoparaphyllia, and exostome borders more strongly widened where the pattern changes from cross striolate to papillose. In addition, D. arcticus, D. cardotii, and the members of Campylium almost always have a short double costa.