BFNA Title: Porotrichum
XX. POROTRICHUM (Bridel) Hampe, Linnaea 32: 154. 1863. * [Latin poro, pore, and trich, hair, alluding to the perforated inner peristome segments]
Inés Sastre-De Jesús
Climacium subgen. Porotrichum Bridel, Bryol. Univ. 2: 275. 1827
Plants dendroid, short to long-stipitate, complanate. Primary stem creeping, turning perpendicular to substrate and forming a stipe, mostly pinnate to sparsely branched distally. Paraphyllia absent. Stem leaves and branch leaves complanate, erect, smooth; margins serrate [slightly serrate]; costa single, slender, tapering toward apex. Inner perichaetial leaves broadly lanceolate-subulate, margins serrate distally; costa absent or present; distal median cells fusiform to linear. Seta mostly reddish brown, to 2.5 cm. Capsule erect to horizontal, oblong-ovoid; exostome teeth lanceolate from a broad base tapering toward apex, at back with strongly projecting lamellae, mostly papillose; endostome with a high basal membrane, segments papillose to sparsely papillose, perforate, cilia present. Spores 13 \um.
Porotrichum species are distinguished in the Neckeraceae by leaves with apex serrate and costa tapering toward the apex. In the flora, the genus is represented by only one species, while the tropics hold the largest diversity.
Species 40 (1 in the flora): North America, Mexico, West Indies, Central America, South America, Asia, Africa, Pacific Islands (New Zealand).
1. Porotrichum bigelovii (Sullivant) Kindberg, Canad. Rec. Sci. 6: 18. 1894
Hypnum bigelovii Sullivant, Expl. Railroad
Plants medium-sized 2--5 cm, light- shiny green to golden green. Creeping stem leaves 1--2 mm, erect-spreading, deltoid, acute; margins entire to slightly serrulate, plane; costa short-double or single; apical cells elongate-rhomboidal, 5--8 \um, basal cells elongate-rhomboidal, 4--10 x 1 \um, smooth. Stipe leaves erect-spreading, spreading, deltoid, acute, margins serrulate, plane; costa present, single; apical cells elongate-rhomboidal, basal cells rectangular, smooth. Stem leaves ovate-oblong, 2.5--3 mm; acute; margins serrate at apex; apical cells rhombic to rhomboidal, 3--5 x 2--3 \um, median cells rectangular, 5--10 x 1.5 \um, basal cells rectangular, 8.5 x 1.5 \um. Branch leaves erect to erect-spreading, ovate-oblong, smaller than stem leaves, ca. 1.5 mm; serrate at apex, acute; costa single, reaching to 3/4 the leaf length; apical cells rhombic 3--3.5 x 2 \um; median cells rectangular 3.5--6.5 x 2 \um; basal cells rectangular. 7--10 x 2.5--3.0 \um. Sexual condition dioicous.
Capsules mature Mar--Aug. Mostly on soil, rocks, logs, under shaded cliffs or shaded boulders by streams, crevices of wet rocks in forests of Douglas Fir, Red Cedar, Redwood, black oak; 0--600 m; B.C.; Calif., Idaho, Oreg., Wash.
In the flora Porotrichum bigelovii is immediately distinguished from other dendroid mosses by its soft appearance due to the complanate leaves and stem. In addition, the costa narrowing toward the apex separates it from Thamnobryum.