Seeds

Seeds are the reproductive units of seed plants, produced by mature ovules after fertilization. They enable dispersal and persistence across seasons. A seed typically contains an embryo capable of growing into a new plant, a nutritive tissue to feed the embryo, and a protective outer coating called the seed coat.

An embryo consists of a radicle (future root) and a plumule (future shoot). Many seeds have cotyledons that store or supply nutrients to the seedling. The nutritive tissue is endosperm in many angiosperms; in others, the endosperm is absorbed by the embryo and nutrients reside in the cotyledons. The seed coat, arising from the ovule’s outer layers, protects the seed; the hilum marks attachment, and the micropyle is a pore for water entry.

Seed development follows fertilization. In flowering plants, double fertilization produces a zygote and endosperm. Mature seeds often enter dormancy, delaying germination until conditions are suitable. Dormancy can be physiological or physical, and seeds are adapted to resist desiccation and survive dry periods.

Dispersal spreads seeds by wind, water, animals, or self-ejection, enabling colonization away from the parent plant. Germination begins when moisture, temperature, and oxygen are adequate, with the radicle emerging to form a root and the plumule forming a shoot. Some species require stratification (cold treatment) or scarification (coating disruption) to break dormancy.

Seeds underpin agriculture, forestry, and biodiversity preservation. They supply most staple crops, contribute to reforestation, and serve as material for breeding programs. Seed banks and controlled storage help conserve genetic resources and maintain seed viability over time.