Syngamy, Embryo Development and Seed Dispersal

Abstract

The basic plan in modern conifers is conserved through organelle exclusion and zygote formation, proembryo development, early embryogeny and late ernbryogeny. Virtually all conifers have some type of polyembryony but not all have multiple archegonia. The ovule, once fertilized, develops into a seed. Each developing embryo is nourished by the female gametophyte as it grows out of its archegonium into the corrosion cavity. If it survives intense competition to become the dominant embryo, then it will develop a root meristem elongating in the direction of the micropyle and a shoot meristem elongating in the direction of the chalaza. A single, dominant embryo reaches maturity prior to seed dispersal. Seed dispersal occurs by wind but humans, birds and other vertebrates play an important role too.