AbstractOvules of the raspberry, Rubus idaeus L., resembled those of other Rubus species in being unitegmic, crassinucellate, and anatropous. In one cultivar, ‘M. 69/139’, both egg cell and embryo were inserted slightly laterally to the micropyle. Of the tetraploid forms, 4n M. 69/139 showed a proportion of embryo sacs with delayed differentiation, and 4n ‘M. Jewel’ some with four antipodal cells. Embryo development showed little uniformity in timing, but followed the Asterad type.
Occasional delayed endosperm development seemed to be a varietal peculiarity of M. 69/139. At maturity, the ergastic material in healthy endosperms consisted of oil globules and aleuron grains. The hypostase formed a projecting pedestal below the endosperrn at 8 days. The inner epidermal layer of the testa appeared specialized, both in the early stages of seed growth, when it is suggested that it functioned as an endodermis, and at maturity, when it appeared to form an osmotic barrier.