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Leucodontaceae Schimp. Search in NYBG Virtual HerbariumAfrican Plants, Senckenberg Photo GallerySearch in Flora do Brasil 2020Search in Reflora - Virtual HerbariumSearch in Living Collections Decrease font Increase font Restore font
 

Published In: Corollarium Bryologiae Europaeae 108. 1856. (Coroll. Bryol. Eur.) Name publication detail
 

Project Name Data (Last Modified On 1/8/2014)
Acceptance : Accepted
Project data     (Last Modified On 1/8/2014)
Discussion :

The circumscription of the Leucodontaceae is unsettled, and there are many different opinions on the limits of the family (see, e.g.,Fleischer 1908; Brotherus 1925; Manuel 1974; Akiyama 1994; Buck 1980, 1998; Buck & Goffinet 2000; Goffinet & Buck 2004). The number of genera placed in the fam-ily varies from eleven (Manuel 1974; Walther 1983) to two (Buck 1998). According to Akiyama (1994), establishing morphological limits for the Leucodontaceae is a daunting task because most of the pertinent genera are monospecific, and, since all the genera are epiphytic, character convergence is likely to be high. As treated here the circumscription of Leucodontaceae is narrow and, following Buck (1998) and Akiyama (1994), includes three genera: Leucodon Schwägr. (39 species), Leu-codontella Nog. (1 species), and Pterogoniadelphus M. Fleisch. (= Felipponea; 3 species). The three genera are exceedingly close; Akiyama (1988, 1994) in fact treats Leucodontella as a subgenus of Leucodon.

Members of the Leucodontaceae have creeping stolons with erect or pendent secondary stems that lack paraphyllia. The stolons and stems may or may not have internal differentiation, and pseudoparaphyllia can be present or absent. The rhizoids are nearly unbranched and generally come from circular clusters of initials abaxial to the leaf insertions. The leaves are ecostate. The leaf cells are thick-walled, usually smooth, and the basal cells in the alar region are quadrate to oblate. Mem-bers of the Leucodontaceae are dioicous, and they often have strongly differentiated perichaetial leaves, immersed, emergent or long-exserted capsules, reduced peristomes, and cucullate calyptrae. The peristomes of Leucodontella and Pterogoniadelphus lack prostomial development, and this feature is also lacking in some species of Leucodon. Leucodontella is distinguished from the other members of the family by its endostomial morphology: high basal membrane and short segments. Pterogoniadelphus differs from Leucodon only in having more extensively developed alar cells.


 

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Plants slender to robust in dense, usually epiphytic mats. Primary stems creeping. Secondary stems horizontal or erect, irregularly branched; cross section with sclerodermis, firm-walled cortex, central strand present or absent; paraphyllia absent; pseudoparaphyllia present or absent, scale leaves present; rhizoids from circular clusters of initials abaxial to the leaf insertions. Leaves ovate-lanceolate, smooth or plicate, often secund when dry, acute or acuminate, slightly decurrent; margins plane or re-curved at base; costa absent; cells smooth, occasionally mammillose to prorate, sometimes porose, thick-walled, apical and median cells linear to fusiform; basal median cells linear, often porose; alar cells quadrate to oblate. Dioicous. Perichaetial leaves convolute-sheathing. Setae elongate. Capsules immersed, emergent or variously exserted, subglobose, oblong-ellipsoid, or cylindrical, smooth or furrowed when dry; stomata present or absent; opercula rostrate to obliquely rostrate; annuli rudi-mentary, cells clinging to the operculum base and capsule mouth after dehiscence; peristome diplolepideous, properistome at times well developed; exostome teeth narrowly triangular, at times chambered, yellowish white, variously papillose; endostome basal membranes low, pale, lightly pa-pillose, segments and cilia absent, rarely with a high basal membrane and low segments. Spores small and round or large and irregularly oblong, exosporically or endosporically germinated. Calyptrae cu-cullate, smooth, naked.

 

Lower Taxa
 

 
 
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