XVI International Botanical Congess

Pattern of vegetative propagules is disputable. On the example of Hammarbya paludosa (H.p) (Orchidaceae, Kalanchoe pinnata (K.p.) and K. daigremontiana (K.d.) (Crassulaceae) the propagule morphogenesis was examined in detail. Reproduction via propagules is characteristic for H.p. and K.d., but in K.p. it occurs only at stress situation. The propagule of H.p. is a unique unit of vegetative reproduction for Orchidaceae which appears (exogenously) due to epidermal cells' divisions on adaxial side of leaf tip (rarely of the bracts). The meristematic primordium has a dorsoventral structure. Formed propagule consists of the outer (the first leaf) and inner parts (shoot apex with two leaf primordia). One of the peculiarities of propagule morphogenesis are similar to adventive bud and another - to a pseudobulb. Besides, certain stages of propagule development can be likened to somatic embryo, protocorm, or seedling of orchids. In both species of Kalanchoe propagules are formed at the leaf margin (endogenously) from especial dormant-meristems" in the leaves notches. Differences are concerning with the site of root initiation and presence of dormancy period (in K.d. - absent). These propagules can be classified as transitional forms between somatic embryo and bud.