Vegetative reproduction and clonal diversity in Rhytidium rugosum (Rhytidiaceae, Bryopsida) inferred by morpho-anatomical and molecular analyses

Many bryophytes exhibit specific life forms that result in the formation of distinct patches. This is primarily achieved by 'consequent vegetative multiplication' through indeterminate growth and vegetative reproduction. Little, however, is known about the underlying mechanisms and genetic patterns. In this study on vegetative multiplication in bryophytes, we apply morpho-anatomical and molecular (AFLP fingerprinting) techniques to analyze the vegetative reproduction system, clonal diversity, and habitat colonization of a pleurocarpous moss, Rhytidium rugosum (Rhytidiaceae). Morpho-anatomically, three types of vegetative diaspores are identified and illustrated: ramets, separated after decay and disintegration of older shoot parts (clonal reproduction); brood branches/branchlets; and caducous shoot apices (both vegetative reproduction s.str.). The AFLP fingerprinting of 35 samples (from two plots in Thuringia, further German populations, and from France, Russia, and Canada) resulted in the identification of three clones from the two plots, each comprising two to 15 samples with identical fingerprints. Samples from one clone occurred in both plots, thus proving dispersal of vegetative diaspores. The AFLP analysis further revealed close relationships of the plot samples, which suggest a clonal rather than generative (sexual) origin of the population.