Leucobryaceae
Dioicous, pseudoautoicous, with male plants dwarfed and embedded in the tomentum or on leaves of female plants, or rarely paroicous (not in Victoria). Asexual reproduction often by fragile shoot apices detaching as comose clusters of apical leaves, by caducous leaves with rhizoids or axillary gemmae (not in Victoria). Turves or cushions on soil, rocks, logs or tree ferns or tree trunks. Stems erect, simple, forked or sparingly branched, with sparse rhizoids to tomentose; central strand present or absent. Leaves arranged around the stem facing all directions, monomorphic, erecto-patent, secund or curved outwards when moist, hardly altered becoming appressed when dry; apex acuminate, acute, apiculate or rounded, concolourous or hyaline, sometimes with a hairpoint, sometimes bearing rhizoids; costa broad, usually occupying more than 1/3 of leaf base at base, often occupying most of the leaf width and giving the appearance of being absent, subpercurrent to excurrent, composed of layers of hyaline leucocyst cells interconnected by pores with intervening narrower and single layered chlorophyllose chlorocyst cells (‘Leucobryoid costa’) or differentiated into an adaxial layer of enlarged hyalocyst cells, epidermal cells or stereids, a central layer of guide cells and an abaxial layer of stereids and substereids alternating with guide cells; margins entire to serrate, plane or incurved, sometimes with a short border of hyaline cells above the alar cells; lamina cells elliptic, rhomboidal, rectangular or isodiametric, smooth or pitted, often confined to a small marginal band and appearing like a border; alar cells well differentiated to not differentiated, 1- or 2-layered, enlarged or not. Acrocarpous. Calyptra cucullate or mitrate (not in Victoria), smooth, glaborus, sometimes fimbriate at basal edge. Capsules exserted, erect to pendulous, straight or curved, operculate. Operculum rostrate. Peristome a single series of 16 teeth, split in upper half or to the base into filaments.
Cosmopolitan with 14 genera and around 270 species; 2 genera and nine species in Victoria.
The circumscription of Leucobryaceae here follows La Farge et al. (2000, 2002) in including taxa such as Campylopus that have previously been recognised in the subfamily Campylopodioideae of a more broadly defined Dicranaceae. This placement is a response to phylogenetic analyses of chloroplast DNA sequences that show the Campylopodioideae to be closer related to the Leucobryaceae than to Dicranaceae (e.g. Stech et al. 1999; La Farge et al. 2000, 2002). In its traditional circumscription, the Leucobryaceae was reserved for genera that had a Leucobryoid costa (i.e. broad and composed of both leucocysts and chlorocysts). In its expanded concept, adopted here, which includes former taxa of the Dicranaceae like Campylopus, the costa is almost always very broad, but can be Leucobryoid or not (La Farge et al. 2000).
SpinningLa Farge, C.; Mishler, B.D.; Wheeler, J.A.; Wall, D.P.; Johannes, K. (2000). Phylogenetic relationships within the haplolepidous mosses. The Bryologist 103(2): 257–276.
La Farge, C.; Shaw, A.J.; Vitt, D.H. (2002). The circumscription of the Dicranaceae (Bryopsida) based on the chloroplast regions trnL-trnF and rps4. Systematic Botany 27: 435–452.
Stech, M. (1999). A reclassification of Dicranaceae (Bryopsida) based on non-coding cpDNA sequence data. Journal of the Hattori Botanical Laboratory 86: 137–159.
