spermatophyte

Spermatophytes, or seed plants, comprise the group of vascular plants that reproduce by seeds rather than spores. They form a monophyletic lineage that includes two major clades: gymnosperms (conifers, cycads, Ginkgo, and gnetophytes) and angiosperms (flowering plants).

In spermatophytes, the dominant phase of the life cycle is the sporophyte; the gametophytes are reduced and dependent on the sporophyte. Reproduction involves pollen grains, which contain the male gametophyte, and ovules, which contain the female gametophyte. Pollen is delivered by wind or animals to the ovule, enabling fertilization. After fertilization, the ovule develops into a seed, which contains an embryo and, in many species, nutritive tissue such as endosperm. The seed is protected by integuments that become the seed coat.

Gymnosperms produce naked seeds borne on cones or other reproductive structures; angiosperms form seeds within ovaries that mature into fruits. Angiosperms exhibit double fertilization, in which one sperm cell fertilizes the egg to form a zygote and another fuses with two polar nuclei to form a triploid endosperm, providing nourishment to the developing embryo.

Spermatophytes are the most widespread and diverse group of land plants. Angiosperms dominate contemporary terrestrial ecosystems in species richness and biomass, while gymnosperms are prominent in many ecosystems and include ecologically and economically important groups such as conifers. They are of major ecological and economic importance for timber, crops, and horticulture.