As much as Colleen hated to admit it, the "Doomsday Seeds" video inspired her to learn more about seed plants, or spermatophytes, as her parents referred to them.

Recall that there are two main types of plants: nonvascular plants and vascular plants. Seed plants and seedless plants are the two types of vascular plants. Seed plants, called spermatophytes are divided into the cone-bearing plants (gymnosperms) and flowering plants (angiosperms). Colleen discovered that spermatophytes are the most biologically successful plants since they represent the majority of the plant kingdom. Click the images below to learn about the characteristics of spermatophytes that which help them to be the most biologically successful plants.