Anatomical and morphological studies of seed development in Sandersonia aurantiaca (Hook.)

Seed development, including the development of the embryo, the endosperm and the seed coat of Sandersonia aurantiaca (Hook.) has been studied. Seed development in S. aurantiaca takes about 60 days from pollination to maturity. The embryo passes through the early globular, the late globular and the elongated spheroidal stages before reaching the linear embryo stage. Endosperm development conforms to the nuclear type. The cellularisation of the endosperm starts at about 14 days after pollination (DAP) when the embryo reaches the early globular stage, and terminates at about 21 DAP when the embryo is in the late globular stage. The mature seed is globose with a strophiole around the micropyle. The embryo is linear and shows a prominent radicle, a small embryonic axis, shoot apex and large cotyledon. The endosperm constitutes most of the seed volume and contains cells with thickened walls and many storage bodies. The seed coat of a mature seed differentiates into three layers: the epidermis, the subepidermal parenchyma (middle layer), and the lignified layer. Both epidermis and subepidermis come from the outer integument. The lignified layer is derived from both the outer and inner, or only the inner integument