VEGETATIVE DIVERSIFICATION AND RADIATION IN SUBTRIBE DENDROBIINAE (ORCHIDACEAE) - EVIDENCE FROM CHLOROPLAST DNA PHYLOGENY AND ANATOMICAL CHARACTERS

The data derived from a chloroplast DNA restriction site analysis of s ubtribe Dendrobiinae (Orchidaceae) indicate that extreme vegetative di versification is concentrated in two limited parts of this group. Over laying the vegetative character states onto the chloroplast DNA cladog ram suggests that several xeromorphic, vegetative characters evolved i n the lines leading to the above-mentioned clades. Several anatomical characters are also associated with xeromorphy. These vegetative and a natomical characters facilitated the establishment of this group in va rious dry habitats. On the other hand, the modifications of size and n umber of parenchymatous cells substantially contributed to the vegetat ive diversification. This fact implies that a simple structural adjust ment can result in a major modification of growth habits in the Dendro biinae.