The non-flowering plants encompass all of those green plants that are not in the flowering plant division. Most of these trees are coniferous trees, sometimes referred to as pines, but there are also gingkos and cycads in this category.
These groups of plants are often wind-pollinated and their seeds are wind-dispersed. The non-flowering plants have their origins almost three hundred million years ago, far earlier than the flowering plants.
Most of the non-flowering plants in the study were of the true pine family (firs, spruces, and pines), the araucaria family (Norfolk Island and Bunya trees). The branching cycads are from an even earlier lineage. All of these trees are descendants of plants groups that once dominated the world.
From Wikipedia:
The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and Gnetales. The term “gymnosperm” comes from the Greek word gymnospermos meaning “naked seeds”, after the unenclosed condition of their seeds (called ovules in their unfertilized state). Their naked condition stands in contrast to the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, often modified to form cones, or at the end of short stalks as in (Ginkgo).
The gymnosperms and angiosperms together compose the spermatophytes or seed plants. By far the largest group of living gymnosperms is the conifers (pines, cypresses, and relatives), followed by cycads, Gnetophytes (Gnetophyta, Ephedra and Welwitschia), and Ginkgo (a single living species).
