The upright trunks of the tulip tree (Liriodendron tulipifera) grace the forests of the Eastern United States, in an area east of the Mississippi River and south of the Great Lakes. The tulip tree is also regionally called tulip poplar or yellow poplar. The reference to tulip centers on both the shape of the leaves as well as the pale yellow-green flower with orange markings. Tulip tree flowers occur on branch tips high up in the canopy, so they're difficult to see.
Across its native range, which spans across U.S. Department of Agriculture plant hardiness zones 5b through 9a, the tulip tree blooms anytime from late April to mid-June. The weather conditions can change the flowering time frame. Cool, cloudy weather delays flowering while unusually warm weather moves the flowering season earlier than average. Trees display the flowers anywhere from two to six weeks. Size and age of tree varies the length of the flowering period.
Once a sapling tulip tree reaches the age of 15 to 20 years old, it produces its first flowers. A sunny location promotes earlier and more flowers on branch tips compared to trees in shadier conditions. Tulip trees are long-lived, and they continue to bloom each late spring for as long as 200 years.
Tulip trees in the Deep South, along the Gulf Coast and Northern Florida, begin to bloom in early to mid-April. The beginning of flowering occurs progressively later the farther north traveled. In the North Carolina Piedmont, flowering starts around May 1, but on average in mid-May in St. Louis. In Washington, D.C., the tulip tree is blooming by the second week in May. Around Boston, it flowers in June.
A tulip tree's flowers occur after the leaves appear and have reached full size. The leaves mask the flowers, and often fallen petals or old flowers on the ground are the only hints the trees is or was blooming. Each blossom measures 2 inches across and is cup-shaped or tuliplike. Six light-yellow petals have a bold orange base. Flies, beetles, honeybees and bumblebees pollinate the flowers, which are receptive to pollen on the female pistil organ for only 12 to 24 hours.