Development of ovule and seed in Begonia squamulosa Hook. F.

In spite of the dizonate structure of the ovule primordium, the ovule is crassinucellate. Both integuments remain two-layered and become crushed during seed development, the outer layer which differentiates into the exotesta excepted. A transverse ring of specialised testa cells helps to form a special zone of rupture by which the operculum lifts off.