Frøanlæg

Frøanlæg, or seed primordium, is the structure in seed plants that gives rise to seeds. In Danish botanical usage, frøanlæg most commonly refers to the ovule, the immature seed located within the ovary of angiosperms, and to the tissues that participate in seed formation.

Structure: The ovule consists of a central nucellus surrounded by one or more integuments. The opening at the integuments, the micropyle, provides a site for pollen entry in fertilization. Through megasporogenesis the megasporangium produces megaspores, and in most species one megaspore develops into the female gametophyte (embryo sac).

Development and seed formation: After fertilization, the zygote develops into the embryo, and in many angiosperms the central cell with sperm produces endosperm. The integuments thicken to form the seed coat, enclosing the embryo and nutritive tissue. In gymnosperms, seeds develop on the surfaces of scales or leaves and are nourished by the megagametophyte rather than by endosperm.

Relation and diversity: Angiosperms produce seeds inside fruits; gymnosperms produce naked seeds on reproductive structures. The study of frøanlæg is central to understanding plant reproduction, evolution, and seed dispersal strategies, and it highlights key differences in seed development between major plant groups.