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BFNA Title: Pleuroziaceae |
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Work In Progress: PLEUROZIACEAE Barbara M. Thiers
Plants bilaterally symmetrical; rhizomatous branch system present (often obscure), erect stems forming tufts, fans or festoons. Stems strongly differentiated internally into a thick-walled epidermis and thin-walled cortex. Rhizoids restricted to stem bases. Vegetative branches Plagiochila type. Leaves distichous, bases clasping the stem; first stem leaves entire, later leaves usually bilobed, sharply folded and strongly dimorphic. Oil bodies present. Asexual reproduction absent. Underleaves absent. Monoicous or dioicous. Androecia on short branches, 1 antheridium per bract. Gynoecia on short branches, each subtended by a single bract; perianths needle-shaped, plicate (smooth in some extralimital taxa); archegonia 1--7 per gynoecium; (sterile gynoecia, consisting of a bract and a tubular, smooth perianth present in some extralimital species). Sporophytes robust. Seta short, composed of numerous cell rows with no detectable pattern of layering. Capsule subspherical to ovoid, wall 6--8 cell layers thick, outermost cells with nodular thickenings along adjacent cell walls; innermost cell layer covered with fenestrate secondary thickenings; valves straight, divided to base. Elaters bispiral, brown. Spores covered with crowded spines. Germination endosporic.
PLEUROZIA Dumortier, Recueil Observ. Jungerm. 15. 1835.
Plants wine-red. Stem epidermis 1--4 cell rows wide, cortex 8--15 cells wide. Entire leaves broadly ovate to orbicular, apex rounded, margins entire, base rounded to cordate. Bilobed leaves with ventral lobes ovate to orbicular, concave, margins entire to undulate and/or dentate, apex entire, irregularly dentate or shallowly bilobed; dorsal lobules tubular, opening restricted to an aperture complex positioned on adaxial surface near apex or midportion of lobule, access to lobule interior controlled by a hinged, spathulate valve that fits into a concave abutment, valve and abutment oriented toward lobule base, situated in a weakly to well-defined oblong or circular basin bordered or overarched by a rounded lip; lobule attached to lobe for 0.3 or less of lobule length. Oil bodies colorless, granular, 18--28 per cell. Androecial bracts in 4--10 pairs. Gynoecial bract trilobed, obdeltoid, lobes triangular; perianth mouth ciliate, cilia of 3--10 cells, sometimes articulate or branched. Spores 25--50 µm diam., spherical, golden brown.
Species 11, 1 in the flora.
SELECTED REFERENCES Schuster, R. M. 1965. Studies on Hepaticae. XVI. The morphology and systematic position of the suborder Pleuroziinae. Transactions of the British Bryological Society 4: 794—800. Thiers, B. M. 1992. A monograph of Pleurozia (Hepaticae, Pleuroziaceae). Bryologist 96: 517—554. 1993.
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