Embryo and Endosperm Structures of Cycas revoluta Thunb.Seeds

The embryo and endosperm anatomy of Cycas revoluta Thunb.seeds showed that seeds were albuminous,both endosperm and perisperm and involved an erect embryo when mature.The outer skin of the endosperm was deposited by epicuticular wax.The epidermal cells had angle cell nuclei but no starch.The middle cell nucleus was obvious.The inner cells had rich starch granules with a single umbilical point but no visible cell nucleus.The endosperm at the end with blastopores invaginated into a groove as a storage cellar.The mature anatropous embryo was located in the sac formed after the endosperm cells degenerated.The mature embryo accounted for 1/3 to 2/3 of the endosperm and reached physiological maturity,with twin cotyledons vertical and semi-connate.At the base of embryoid was a beak-like protuberance attached to a gut-folded filamentous haustorium with a small sac.The plumule was composed of apical meristem and several pieces of primary leaf with pinnate leaf primordium and fluff precursor.The embryoid had long tubular cells and thickening spiral vessels.Several spiral vessels or annular vessels were clearly visible side-by-side in the cotyledon midrib.