Pireella
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Authority
Buck, William R. 2003. Guide to the plants of central french Guiana. Part 3. Mosses. Mem. New York Bot. Gard. 76: 1-167.
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Family
Pterobryaceae
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Scientific Name
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Description
Genus Description - Plants relatively small to medium-sized or rarely robust, in green to golden, thin to dense, epiphytic colonies; stipes usually frondose and pinnately branched, rarely simple, erect, sometimes becoming flagellate above with reduced leaves. Stipe leaves strongly to slightly differentiated from branch leaves, appressed to squarrose-spreading from a clasping base, ovate-triangular to lanceolate; branch leaves erect to spreading, in 5 obvious spiral rows or not, lanceolate to ovate, broadly acuminate, concave, not plicate, rarely decurrent; margins subentire to serrulate, plane; costa single, usually subpercurrent to percurrent, rarely ending near midleaf, sometimes flexuose, not projecting at apex; cells oval (1.5-3:1) to linear, often prorulose, thin- to thick-walled, sometimes porose, becoming yellow at the insertion; alar cells differentiated in quite small to extensive areas. Asexual propagula often clustered in leaf axils on short stalks, uniseriate. Dioicous, rarely fertile. Setae very short to elongate, smooth or less often roughened, reddish, occasionally flexuose; capsules mostly immersed but occasionally exserted, erect and symmetric, usually broadly oval-cylindric, rarely subglobose; peristome double, prostome often well developed, exostome teeth mostly smooth and perforate; endostome strongly reduced to slender short segments, often fragmentary and adherent to the teeth. Calyptrae (reportedly) cucullate or (observed) mitrate, mostly pilose, smooth. Pireella is characterized by mostly well branched, erect secondary stems arising from a creeping primary stem. The leaves are lanceolate to ovate and the costa usually ends in the acumen. The branch leaves are strongly concave in all species. The cells vary from oval to linear and the alar cells are scarcely differentiated to quadrate in extensive areas. The capsules are mostly immersed and the peristome is double but the endostome is strongly reduced and often difficult to demonstrate. The exostome teeth are mostly unornamented and obscured by a well developed prostome.