Vivipary - Development Biology

In flowering plants the seed or fruit generally is dispersed and germination occurs when the conditions are congenial for growth. However, in some plants growing along the sea shores or in mangrove areas the soil is too saline or salty for seed germination. Moreover, in such places the seed and the young seedlings are likely to get washed away by the tide. Mangrove plants (e.g., Rhizophora spp.) have, therefore, evolved a unique adaptation for ensuring seed germination and nurturing of the young sporophyte.

The young seedling grows out of the intact fruit and hangs with its pointed radicular end facing downward. Once the seedling attains a large size it drops down and penetrates the soil. Roots are produced rapidly by the radicle and the seedling is fixed firmly in the soil. By this time the seedling would have developed an extensive photosynthetic tissue to ensure its establishment and has been compared to the similar state observed in mammals. Certain bamboos and forest trees also practice vivipary. This mechanism of rearing the young one by the parent is termed vivipary. It is a specialized characteristic evolved by mangrove plants as a strategy for survival.