Plants that do not have flowers are called non-flowering plants.Some of them are seed bearing plants like conifers but their seeds are not enclosed in fruit and have naked seeds.They are called gymnosperms.Examples are spruce,pine,fir, cedar etc.Some non-flowering plants are seedless like ferns, liverworts,algae and mosses.They are called simple plants.Since they lack seeds,they produce spores for survival.
There are many different types of plants that do not produce flowers and despite the difference in their shape, size, color and chemistry, all of them are classified as nonflowering. The very first plants on earth were marine nonflowering plants. It is estimated that nonflowering plants started to grow on land about 450 million years ago. For the next 320 years all plants remained nonflowering. This is the reason why there is a greater variety of nonflowering plants in the world than the flowering kind.