No. Although most of the world’s plants are flowering plants called angiosperms (from the Greek words for “vessel” and “seed”), there are hundreds of plants that do not make flowers. Seed plants that do not have flowers—such as cycads, ginkgo, and conifers—are called gymnosperms. Conifers, for example, are common gymnosperms; instead of flowers, conifers have cones that produce pollen or eggs. Well-known examples are cedars, cypresses, Douglas firs, junipers, pines, redwoods, and spruces.
Male cones are small and soft, and female cones are large and hard. Wind carries pollen from the male cone to the female cone. As the eggs are pollinated and seeds develop, the scales of the cone open up to release the seeds. Once the seeds take root, a new plant grows. Other plants that do not have flowers are mosses; although they sometimes look like they are blooming, the flower-like part is a little capsule full of spores at the end of a small stem.