Development of Ovule, Embryo Sac and Embryo in Three Species of Mulberry (Morus L.)

This article reveals the comparative studies on development of ovule, embryo sac and embryo of three species of genus morus namely, Morus cathyana, Morus laevigata and Morus nigra, through microtone sections. Commonly, in all the three species, the pistil is bicarpellary, syncorpous having unilocular ovary with a bitegmic ovule on marginal placenta. The matured ovule is anatropous in M. nigra and hemitropous in M. cathyana and M. laevigata. The micropyle is formed by both outer and inner integuments in M. nigra while it is formed only by the inner integuments in other two species. In M. Laevigata, embryo sac develops only in 12% of the ovules. Occasionally, the antipodal cells become hypertrophied with large vacuoles in M. nigra. The hypostase is not conspicuous in M. nigra unlike other two species. The phylogenetic significance of these variations in embryological features are discussed in comparisons with other related species and genera