Morphogenesis of Spirodela oligorrhiza: Ontogenesis of Fronds

The ontogeny of fronds in Spirodela oligorrhiza (Kurz) Hegelm. (Lemnaceae) was investigated in detail by means of morphological, anatomical, and autoradiographic methods. The initiation of a new frond takes place in a bud not more than 18 cells long. Thus, when the young frond protrudes from the reproductive pocket of its mother frond, it already contains at least two younger generations of vegetative buds. During differentiation of a frond, the meristematic area, located near the nodal embryonic point, first contributes cells to the aerenchymatous distal portion of the frond and only later contributes cells to the proximal end.