Gymnosperms

Gymnosperms are seed plants whose seeds develop exposed on cones or on modified leaves, not within a fruit. The seeds are not enclosed by an ovary. Four living phyla comprise the group: Pinophyta (conifers), Cycadophyta (cycads), Ginkgophyta (Ginkgo), and Gnetophyta (Ephedra, Gnetum, Welwitschia). Gymnosperms are distinguished from angiosperms by the absence of flowers and fruits, and by naked seeds that are often borne on scales.

Life cycle is sporophyte-dominant. Microspores form pollen; megaspores form ovules. Pollen is usually wind-dispersed. After pollination, fertilization produces a seed that matures on the parent plant and is dispersed by wind, animals, or gravity. Seeds often have a nutritive tissue derived from the female gametophyte.

Historically dominant in the Paleozoic and Mesozoic, gymnosperms are now less diverse than angiosperms but remain ecologically important, especially in boreal and arid regions. They typically have needle-like or scale-like leaves and produce wood with secondary growth. Adaptations include resilience to drought and cold.

Economically, gymnosperms provide timber, resin, and ornamentals; several species are cultivated widely. Some are threatened by habitat loss, climate change, and overexploitation, leading to conservation concerns and programs to protect genetic diversity and habitats.