Which type of plants is characterized by having seeds that are not enclosed in an ovary?

The type of plants characterized by having seeds that are not enclosed in an ovary is gymnosperms. Gymnosperms are a group of seed-producing plants that include conifers, cycads, ginkgo, and gnetophytes. The key feature of gymnosperms is that their seeds are exposed on cones or other structures rather than enclosed within a fruit, which distinguishes them from angiosperms, where seeds develop within an ovary that becomes the fruit.

Angiosperms, in contrast, are defined by having flowers and seeds protected by an ovary. Ferns and mosses are not seed-producing plants at all; they reproduce through spores rather than seeds. This fundamental characteristic is what sets gymnosperms apart within the plant kingdom, making them unique in their reproductive methods and seed development.