Distichous and Pseudodistichous Mosses

In revising the family Phyllogoniaceae for the Flora Malesiana, I found that in many species which so far were included in this family, the leaves are, contrary to expectation not distichously disposed. As that type of phyllotaxis is regarded as the main diagnostic character of the family, it was a surprise to me that other bryologists had not noticed this fact. For this reason I have paid special attention to the phyllotaxis of the species belonging to the Phyllogoniaceae. In Brotherus, Naturl. Pflanzf. ed. 2, 11 (1925) 175, the family includes three genera, viz. Phyllogonium Brid., Orthorrhynchium Reichdt. and Eucatagonium (Broth.) Fleisch. The first genus, Phyllogonium, comprises, as far as I could check, distichophyllous species only (Fig. 5a). The leaves are inserted alternately on the complanate branches, the distances between the consecutive leaves in both rows being equal. The genus is restricted to S. America and Africa (Congo), and is characterized by the well-marked alar cells and by the strongly ampliate leaf bases.