Monographs Details: Drepanocladus aduncus Warnst.
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Species Description - Plants relatively robust, in stiff to soft, ± lustrous, green to yellow-green, golden, or brown mats or tufts. Stems creeping, ascending to suberect, or floating, to 30 cm long, irregularly to pinnately branched ± in a single plane, the branches often curved; in cross-section without a hyalodermis, with (1-)2(-3) rows of small thick-walled golden cells (that strip off with the leaves on dissection) surrounding larger thin-walled cells, central strand small, of very small thin-walled cells; paraphyllia absent; pseudo-paraphyllia foliose; axillary hairs with 1-2 short brown basal cells and 1-2 elongate hyaline distal cells. Stem and branch leaves similar, crowded, erect to strongly falcate-secund throughout the leaf (i.e., not just in apical portions of leaves), ovate-lanceolate, the stem leaves to ca. 3.5 mm long, those of the branches to ca. 2.2 mm long, gradually acuminate to a flat or channeled acumen; margins entire or rarely subentire, plane to erect; costa single, ending 1/2-4/5 the leaf length; cells long-hexagonal to linear, 610:1, smooth, firm-walled and ± porose; alar cells usually abruptly differentiated in auriculate groups, not reaching the costa, enlarged, inflated, often with a single marginal row of narrow, short- to long-rectangular cells, the inner ones broader, rounded-rectangular, in (2-)3-4(-5) rows from top to bottom, in some leaves with only a few quadrate cells. Asexual propagula none. Dioicous. [Sporophytes unknown from the West Indies; the description based on European material.] Perichaetia enlarged, conspicuous; leaves erect, sheathing, oblong-lanceolate, to ca. 5.3 mm long, ± abruptly narrowly long-acuminate, subpiliferous, plicate; margins entire, plane to erect; costa single, ending near midleaf; cells linear, smooth, firm- to thick-walled, ± porose, becoming shorter, broader, rectangular, and laxer toward the insertion; alar cells not or slightly differentiated in extreme angles. Setae elongate, smooth, reddish, to ca. 6 cm long, twisted; capsules inclined, arcuate, asymmetric, cylindric, with a long neck, 2-2.8 mm long, only slightly constricted below the mouth when dry; exothecial cells rounded-quadrate to short-rectangular, firm-walled; annulus of (1-) 2-3(-4) rows of thick-walled large-lumened cells, deciduous; operculum conic-apiculate; exostome teeth yellow-brown, shouldered, strongly bordered, on the front surface cross-striolate below with overlying fine papillae, coarsely papillose above, trabeculate at back; endostome smooth, with a high basal membrane, segments ± narrow, keeled, narrowly perforate, cilia mostly paired, almost as long as the segments, very slender, nodulose. Spores spherical, finely papillose, 16-21 µm diam. Calyptrae cucullate, naked, smooth.
Discussion:1. Drepanocladus aduncus (Hedw.) Warnst., Beih. Bot. Centralbl. 13: 400. 1903; Hypnum aduncum Hedw., Sp. Musc. Frond. 295. 1801; Amblystegium aduncum (Hedw.) De Not., Comment. Soc. Crittogam. Ital. 2: 290 [reprinted as: Cronaca Briol. Ital. 2: 24]. 1867; Harpidium aduncum (Hedw.) Conard, Bryologist 48: 106. 1945, comb, inval. Plate 85
Discussion. Drepanocladus aduncus is characterized by ovate-lanceolate leaves with entire margins, a costa ending far below the leaf apex, and abruptly enlarged and inflated alar cells. In the West Indies two varieties of this wide-ranging species are found.