Monographs Details: Forsstroemia
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants medium-sized, in green to golden, mostly thin but sometimes extensive, epiphytic colonies. Primary stems creeping, slender, inconspicuous, with reduced, scale-like leaves, turning ca. 90° and becoming the erect secondary stem, the creeping stem continuing by a bud from near the base of the secondary stem, secondary stems ± erect, irregularly pinnate to subfrondose, the branches curved or straight when dry, not or scarcely complanate-foliate; in cross-section with small thick-walled cells surrounding larger thinner-walled cells, central strand none; paraphyllia none; pseudoparaphyllia narrowly foliose; axillary hairs with 1(-2) short brown basal cells and ca. 3 elongate hyaline distal cells. Secondary stem and branch leaves similar but branch leaves smaller, erect-appressed when dry, rapidly erect- to wide-spreading when moist, lanceolate to broadly oblong-ovate, acute to short-acuminate, concave, not or somewhat plicate, short-decurrent; margins entire to serrulate above, entire below, plane above, usually recurved in lower 1/2; costa typically single and ending above midleaf, weak to strong, or rarely short and double; cells elliptic to linear, smooth, firm- to thick-walled, sometimes porose; alar cells numerous, quadrate to oblate, extending up the margins to ca. 1/3 the leaf length. Asexual propagula none. Autoicous or dioicous. Perichaetia conspicuous; leaves strongly differentiated, erect, ± convolute, usually oblong-lanceolate, gradually or abruptly long-acuminate; costa single or absent; cells linear, smooth, firm- to thick-walled, sometimes porose. Setae short, smooth, reddish, often twisted when dry, straight when moist, from a hairy vaginula; capsules immersed to short-exserted, erect and symmetric, cylindric; exothecial cells rectangular, thin- to firm-walled; annulus not differentiated; operculum obliquely conic-rostrate; peristome double or endostome apparently absent, inserted slightly below the mouth, exostome teeth pale, linear-triangular, smooth to finely papillose, on the front surface with a ± straight median line, not or scarcely trabeculate at back; endostome rudimentary to absent, often fragmentary and adhering to exostome. Spores spherical, finely papillose. Calyptrae cucullate, hairy, smooth.
Discussion:Forsstroemia Lindb., Òfvers. Fõrh. Kongl. Svenska Vetensk.-Akad. 19: 605. 1863.
Lusia P. Beauv., Mag. Encycl. 5: 315. 1804, hom. illeg., non Lour., FI. Cochinch. 1: 81. 1790 [Araceae]; Leptodon subgen. Lcisia (P. Beauv.) Endl., Gen. PI. 56. 1836; Neckera sect. Leucodon subsect. Lasia (P. Beauv.) Müll. Hal., Syn. Musc. Frond. 2: 116. 1850.
Dusenia Broth., Bot. Jahrb. Syst. 20: 195. 1894, nom. illeg., non O. Hoffm. in Dusén, Wiss. Ergebn. Schwed. Exped. Magellanslandern 3: 246. 1900 [Asteraceae].
Discussion. Forsstmemia has mostly irregularly branched secondary stems, unicostate leaves with firm- to thick-walled cells and extensive alar differentiation, immersed to shortly exserted, exannulate capsules with pale exostomes and rudimentary endostomes, and hairy cucullate calyptrae. The genus can be divided into two sections: sect. Forsstmemia, with weak costae and elongate cells, and sect. Microforsstroemia Nog., with strong costae and short cells. The genus was recently monographed by Stark (1987), who recognized 10 species. Within our range the genus is represented by a single, seldom collected species.