Monographs Details: Pohlia
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part One: Sphagnales to Bryales. Mem. New York Bot. Gard. 69 (1)
Description:Genus Description - Small to fairly robust plants, usually in small tufts among other mosses, often glossy when dry, pale and whitish to yellowish or dark-green. Gemmae often produced in axils of upper leaves of sterile shoots, with leaf primordia well developed or sometimes rudimentary; rhizoidal tubers occasional. Stems erect, simple or rarely forked near the base when sterile, otherwise branched by innovation, uniformly foliate. Leaves erect to ± spreading, scarcely altered on drying, lanceolate to ovate-lanceolate, sometimes linear-lanceolate, acute to short-acuminate, sometimes ± decurrent; margins coarsely serrate to serrulate near the apex, rarely to the midleaf, plane to ± recurved; costa mostly strong, ending above the midleaf to percurrent, toothed at back above; upper cells linear-rhomboidal to oblong-hexagonal or short-rhomboidal, with thin or ± thickened walls, becoming broader, laxer and ± rectangular toward the base. Dioicous orparoicous, rarely autoicous. Perigonia of dioicous species terminal on simple or innovating stems, with bracts short- to long-acuminate and erect to wide-spreading from an ovate, concave, erect base. Perichaetia terminal on simple or innovating stems. Setae erect, short to long, slender, and flexuose, mostly orange to red; capsules suberect to inclined as much as 180°, shortly urceolate, ± elongate-pyriform, or sometimes linear-cyhndric, with a short or long, distinct neck; annulus none or of (1—)2—3 r-ws of cells, revoluble or irregularly separating; operculum convex or conic to obhquely short-rostrate and blunt; exothecial cells isodiametric to oblong-linear, sometimes bulging, the walls usually evenly thickened, often sinuose; peristome double; exostome teeth yellow- to dark-brown or sometimes white, lanceolate, ± obtuse, acute, or acuminate, sometimes bordered, sometimes trabeculate, papillose to striolate or smooth; endostome hyaline to yellow, the basal membrane very low to high, with segments narrow, flat, and entire to broad, keeled, and widely perforate and cilia none to long and nodulose. Spores 10-30 µm, finely to coarsely papillose.
Pohlia is distinguished by its well-developed double peristome, non-appendiculate cilia, narrow, unbordered leaves that are commonly serrate near the apex, long and usually narrow cells, and well-developed, though non-excurrent costae. Some species of Bryum have narrow cells, but distinctions can be made on the basis of the following: N o Mexican Pohlias have appendiculate cilia, bordered leaves, or excurrent costae. In the absence of sporophytes, neither Pseudopohlia nor Mielichhoferia can be distinguished from Pohlia without some prior knowledge of the individual species.
In this treatment, Pohlia is considered to include Mniobryum (a genus of wet, calcareous clay, with short, urceolate and thin-walled leaf cells).
Pohlias are most common in Mexico at middle to high altitudes where they grow on mineral soil, commonly as weeds. It is therefore surprising that a species as common and widespread as Pohlia nutans has been found in Mexico only once. Pohlia chilensis and P. richardsii, mainly South American in distribution, may occur on Mexico's high volcanic peaks. (Pohlia peracuminata Bartr., of Guatemala, should be referred to Bryum microchaeton Hampe.)
Additional information on the taxonomy ofthe genus can be found in publications by Shaw (1982, 1983).