Vegetative propagation in Rhexia virginica (Melastomataceae): some morphological and ecological considerations

The unusual method of vegetative propagation in the rare shoreline plant Rhexia virginica L. was studied using both histological techniques and observations of the external morphology. Several propagules in the form of swollen tuberouslike roots develop adventitiously early in the spring. As the tuberous root forms its periderm, shedding the cortex and epidermis, a number of root buds develop in the region of the phellogen. Approximately two to four root buds per propagule develop as aerial shoots. The rest of the root buds and the tuberous roots themselves degenerate. There was no evidence of propagules and viable root buds surviving for several years, as previously reported. The inability of the tuberous roots to survive in soil for more than a single year may explain, to some extent, why R. virginica is rare in Ontario.