Ovule and seed development in Vaccinium myrtillus L. [Ericaceae]

Ovule and seed morphogenesis in Vaccinium myrtillus was studied here for the first time. The gynaeceum is paracarpous. The ovules are developed at sutural-angular placentae. Periclinal divisions of the subepidermal cells of the placenta usually precede formation of the ovular primordia. The ovules are ana-campylotropous, medionucellate, unitegmic, leptochalazal and sessile. The initials and dynamics of different ovule structures were determined. The chalazal zone of the nucellus transforms into the postamento-podium. The integument is of dermal origin, with a typical endothelium. The ovule has a hypostase, which is initiated with the beginning of ovular primordium differentiation. It is cup-shaped in the mature ovule and consists of 2-3 layers. Their cell walls are not lignified. The nucellus, integumental parenchyma, endothelium and hypostase do not persist in the mature seed. The latter is exotestal. The embryo sac develops according to the Polygonum type. The endosperm is cellular, with micropylar and chalazal haustoria. The mature embryo is large and well differentiated into organs.