If you want to know what purple-flowering tree is growing in your yard or your neighbor's yard, you're in luck. Only a few spring flowering trees have purple blooms, so identifying them is simple. The most well-known purple flowering trees include lilac, Rose of Sharon, Desert Willow, Eastern Redbud, magnolia and Texas Mountain Laurel. Start by eliminating the trees that don't grow in your climate.
Consider your USDA hardiness zone and geographical location. The Eastern Redbud is native to the east, growing from New Jersey to Florida and west to Missouri, down to Texas and Mexico. Desert Willow grows in arid, dry climates south of USDA hardiness zone 8. Crape myrtle is hardy between zones 6 and 10.
Examine the growth pattern of the tree. Does it have one central trunk or several stems sprouting from the ground? Magnolia and crab apple grow from one central trunk, whereas lilac, Rose of Sharon, crape myrtle and hibiscus are really shrubs, having many stems.
Consider the foliage. The magnolia has shiny green leaves, evergreen in the south. Lilacs have simple, dark green leaves, prone to powdery mildew. Rose of Sharon has compound small leaves born on alternate sides. The Texas Mountain Laurel has foliage with a lacy texture.
Examine the bark for unusual textures or characteristics. Magnolias have silvery gray bark, while crape myrtles have an exfoliating bark that reveals dark brown bark underneath.
Consider the blooms. Rose of Sharon have large, round blooms in a single stem. Lilacs produce mounds of tiny fragrant flowers. Magnolias produce upright, closed blooms, resembling a butterfly at rest.