Hypostase, embryonic sac and endosperm in Anethum graveolens L., and in various families

The presence of pyriform hypostase tissue was investigated before double fertilization till the fusion of free endosperm nuclei in the embryonic sac of A. graveolens. Hypostase a glandular tissue, can secrete its cell contents into the embryonic sac during the development of free endosperm nuclei. Of 78 randomly selected families, 19 display different numbers of species with hypostase. In 15 of these families the hypostase is present together with the Polygonum type of embryonic sac and nuclear type of endosperm.