Monographs Details: Campylium
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants slender to medium-sized, in soft, green to golden to reddish brown, small to extensive, often thin mats. Stems creeping to ascending, irregularly to subpinnately branched; in cross-section without a hyalodermis, with small thick-walled cells surrounding larger firm-walled cells, central strand present (and often collapsed) or absent; paraphyllia absent; pseudoparaphyllia filamentous or slenderly to broadly foliose; axillary hairs with 1-2 short brown basal cells and 1-3 elongate hyaline distal cells. Stem and branch leaves similar but stem leaves somewhat larger and more acuminate, crowded to lax, wide-spreading to squarrose, ovate-lanceolate to broadly ovate, often abruptly tapered to a long, slender, channeled acumen, often concave, mostly cordate at base; margins mostly entire, sometimes serrulate almost to base, plane to erect; costa variable, single and ending only slightly above insertion to somewhat above midleaf, double and almost reaching midleaf or below, or absent; cells long-hexagonal and subflexuose to linear-flexuose, smooth or prorulose, firm-walled and not porose to thick-walled and ± porose throughout, often gradually becoming somewhat longer toward the margins; alar cells differentiated in discrete, often excavate areas in extreme angles or across the entire insertion, quadrate to short-rectangular, often enlarged, sometimes inflated, relatively thin-walled to thick-walled, often colored. Asexual propagula none. Autoicous or dioicous. Perichaetia enlarged, conspicuous; leaves erect, sheathing, oblong-lanceolate, long-acuminate, striate; margins mostly entire, plane to erect; costa short and single or more often absent; cells linear, smooth, firm- to thick-walled, not to strongly porose, becoming shorter, broader, and often thinner-walled toward the insertion, occasionally with numerous firm-walled, quadrate cells in an extensive area across the insertion. Setae elongate, smooth, reddish to orange, not or slightly twisted when dry, straight to curved; capsules inclined to horizontal, arcuate, asymmetric, short-cylindric, usually from a distinct neck; exothecial cells quadrate to short-rectangular, thin- to thick-walled, not collenchymatous; annulus differentiated; operculum short- to long-apiculate from a conic base; exostome teeth yellow-brown, shouldered, strongly bordered, on the front surface cross-striolate below, coarsely papillose above, trabeculate at back; endostome with a high basal membrane, segments keeled, not or narrowly perforate, cilia in groups of 1-3, nodose to appendiculate. Spores spherical, papillose. Calyptrae cucullate, naked, smooth.
Discussion:Campylium (Sull.) Mitt., J. Linn. Soc, Bot. 12: 631. 1869; Hypnum sect. Campylium Sull. in A. Gray, Manual, ed. 2, 677. 1856; Stereodon sect. Campylium (Sull.) Mitt., J. Linn. Soc., Bot. 8: 43. 1864; Hypnum subgen. Campylium (Sull.) A. A. Fisch. Waldh., Bull. Soc. Imp. Naturalistes Moscou 37(3): 37. 1864, Fl;. Bryol. Mosq. 131. 1864.
Amblystegium subgen. Campyliadelphus Lindb., Musci Scand. 32. 1879, nom. nud.; Hypnum sect. Campyliadelphus Kindb., Bih. Kongl. Svenska Vetensk.-Akad. Handl. 7(9): 16. 1883; Amblystegium sect. Campyliadelphus (Kindb.) Braithw., Brit. Moss-Fl. 3: 17. 1896; Campylium sect. Campyliadelphus (Kindb.) Broth, in Engl. & Prantl, Nat. Pflanzenfam. 1(3): 1042. 1908; Campyliadelphus (Kindb.) R. S. Chopra, Tax. Indian Mosses (Bot. Monogr. 10:) 442. 1975.
Chrysohypnum G. Roth, Hedwigia 38(Beibl. 1): 7. 1899, hom. illeg., non Chryso-hypnum Hampe, Bot. Zeitung (Berlin) 28: 35. 1870.
Discussion. Campylium is recognized by its typically wide-spreading to squarrose leaves with a variable costa (within leaves on a single stem), differentiated alar cells, and channeled acumina. The plants often grow in disturbed habitats, such as roadsides and trail banks. Frequently the sites in which the plants are most common are calcareous.
I have debated the value of recognizing Campyliadelphus for Campylium chrysophyllum and its allies. It has long been recognized at a sectional level and more recently it has been elevated to generic status. Andrews (1957) even argued for its exclusion from the Amblystegiaceae. Kanda (1975) put forth a key separating the two genera (as well as Campylophyllum). However, there are no absolute characters separating the genera and I am not convinced that species of Campylium are anything more than reduced members of Campyliadelphus. Admittedly, the two taxa are distinct in aspect, but microscopically they seem to intergrade too uncomfortably to warrant generic recognition. Since the monospecific Campylophyllum is outside of our geographic area, I have not evaluated it thoroughly, but it seems to have more justification as an independent genus than does Campyliadelphus. Hederías (1997) has suggested that Campylium should be split into three genera, and those to be divided among the Amblystegiaceae and Hypnaceae. Such a position, although intriguing, seems to require study greatly beyond the scope of a regional flora.