Some trees produce flowers (angiosperms, i.e., maple) and some do not (gymnosperms, i.e., pine). Flowers are usually grouped together on a stem and are adapted for sexual reproduction. The flower is not an entire plant but an organ formed by some plants for reproductive purposes. 

Trees may be cone-bearing plants (gymnosperms) or flowering plants (angiosperms). Tree ferns are technically not trees as they do not contain wood. All the groups of plants that include trees are vascular plants. This means they have vascular tissues called xylem and phloem.

Redbuds, Flowering Pear trees, Deciduous Magnolias, Dogwood Trees and Ornamental Cherry trees are the earliest spring bloomers. Crape Myrtle trees and the Evergreen Magnolia Trees, Southern and Little Gem, bloom from late spring through summer.