Fissidens pusillissimus

Comprehensive Description

provided by North American Flora
Fissidens pusillissimus Steere, Ann. Bryol. 10: 116. 1938.
Plants exceedingly small, always less than 2 mm. high, usually about 1 mm. ; stems simple, erect when moist, somewhat decurved ventrally when dry; leaves 4-7 pairs, inrolled, slightly shrunken and ventrally falcate-crispate when dry, but not strongly distorted, up to 0.7 X 0.090.10 mm., the lower smaller, the upper oblong-lanceolate, all roimded-obtuse, the costa stout, rather suddenly and strongly bent at a wide angle at about the leaf-middle, ending abruptly well below the leaf -apex; vaginant laminae reaching half the length of the leaf, unequal in width only; dorsal lamina ending gradually or abruptly at the stem; leaf-cells small, obscure, pleuripapillate, the upper median ones nearly isodiametric, up to 5.5 }i in diameter, quadrate to hexagonal, the marginal ones transversely elongate, 7.5 ju X 5.5 ju, with two marginal papillae on the truncate outer surface, the extreme basal cells smooth and somewhat elongated ; dioicous ; male organs not found ; sporophyte terminal ; seta yellow, becoming darker with age, straight, 2 mm. long; capsule erect, symmetric, the urn 0.4 mm. long, less than 0.25 mm. wide, the exothecial cells very strongly convex-swollen and collenchymatous; operculum conic, long-rostrate, about two-thirds the length of the turn.
Type locality: On bark of tree with Pireella cymbifolia (SuU.) Card, on bank of Subin River, Belize District, British Honduras (P. Gentle 1833a) .
Distribution: Known only from the type locality. Ii,i,usTRATiON : Ann. Bryol. 10: 118./. 1-7.
44. Fissidens stenopter3rx Besch. Rev. Bryol.
18: 54. 1891.
Plants more or less gregarious, pale green or brown when old; stems erect, slender and straight, often 2 or 3 together arising from old prostrate stems, seldom more than 5 X 1 mm., usually simple or branching by apical innovations; leaves up to 22 pairs, incurved and twisted when dry, spreading when moist, crowded and overlapping at base, the broader vaginant laminae fitting into the vacant space left by the shorter and narrower dorsal lamina, about 0.66-0.90 X 0.16 mm., lanceolate, the margins entire or obscurely serrulate with tnmcate or bicuspidate smooth cells up to 5 /x in diameter, the cells next the costa larger, up to 8 m, the costa paler, clear and straight below, often bent at the junction of the vaginant laminae and more or less sinuous above the jimction, ending below the 3-4 larger smooth cells of the acute apex; apical cells all hexagonal and dense with thick walls and minute obscure papillae, about 14 rows between costa and margin; vaginant laminae scarcely longer but broader than the apical, ending evenly and obliquely at jimction, the cells longer and broader, the basal juxtacostal cells sometimes up to 13 X 8 m, minutely papillose on the outer surface; dorsal lamina becoming much narrower below the middle of the leaf and tapering to one row of cells or lacking at the base of the leaf; rhizautoicous or autoicous, the antheridia either terminal on tall plants or axillary on the 9 plant in small buds with 2-4 minute bracts and without paraphyses; vaginule dark brown, 0.33 mm. long; seta 0.8-1 mm. long, often bent at base; capsules obovoid-cylindric, ± 0.8 mm. long, contracted under the mouth when dry, the exothecial cells subquadrate to rectangular, collenchymatous ; calyptra extending below the mouth of the capsule, split at base; operculum short-rostrate; peristome-teeth strongly and sharply papillose, inflexed when dry or moist; spores smooth, 15-20 /* in diameter.
Type locality: Border of the Duplessis River, Guadeloupe {Edouard Marie 518). Distribution : Guadeloupe ; Puerto Rico {Steer e) .
bibliographic citation
Robert Statham Williams. 1943. (BRYALES); DICRANACEAE, LEUCOBRYACEAE. North American flora. vol 15(3). New York Botanical Garden, New York, NY
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