Cell walls as taxonomic markers in Polish species of the genus Odontoschisma (Dum.) Dum. (Hepaticae, Cephaloziaceae)

To get valuable diagnostic characters, the structure of cell walls was stud ied with use of two stains (Ruthenium Red -RR- and Resorcine Blue - RB) and in polarized light. As far as the stem structure is concerned, European sp ecies of the genus Odontoschisma fall into two groups: in Odontoschisma elo ngatum and in Odontoschisma macounii a thick, frequently completely obscuri ng cell lumen, "lining layer" is present. It frequently, particularly after staining in RE, detaches from the rest of the cell wall. Such a layer is c ompletely lacking in the two remaining species, viz. O, sphagni and O. denu datum. In polarized light only leaves of O. sphagni show a distinct bright border. The thin cellulose layer (bright in polarized light) embrace the an gular thickenings in O. sphagni and O. denudatum, but is entering the insid e of these thickenings in the two remaining species. Keys for determination of the four European species based an the staining properties of cell wall s and their look in polarized light are provided.