Kentucky's warm summers and moderate winters provide a good growing climate for trees. Annual rainfall of 40 inches a year contributes to the rich variety of tree species. Some trees such as tulip poplar (Liriodendron tulipifera) have a long history of contributions to the people of Kentucky. First used by Native Americans for building canoes, the fast-growing eastern hardwoods were later used by colonists for constructing cabins. In modern times, poplars are valued as urban street trees because of their ornamental spring flowers and broad, shade-producing canopies. A member of the magnolia family, tulip poplar is Kentucky’s state tree, and just one of a variety of native Kentucky magnolia trees.
Kentucky grows the national champion Bigleaf (Magnolia macrophylla), in Tight Hollow, Ky. It reaches 108 feet and has a 42- inch spread. Just as the name implies, Bigleaf magnolia leaves measure between 12 and 36- inches in length, and the fragrant ivory flowers grow 8- to -10 inches across. Bigleaf trees require spacious areas and are most often seen in parks or woodland settings where they provide shade and beauty without litter maintenance. Bigleaf is winter hardy up to USDA planting zone 5.
Horticulturists at the University of Kentucky state that magnolia trees were some of the first flowering trees on earth, but some are revered for more than their flowering abilities. This is the case with cucumbertrees, prized for their fast growth and big shade production. They grow between 50 and 80 feet and have the same size spread. The leaves are smaller than typical magnolias, and the trees are winter hardy to planting zone 4.
Not all of Kentucky’s renowned trees are magnolias; Gymnocladus dioicus is a member of the pea family. Early settlers used the tree’s pods as a coffee substitute, hence the name. The Kentucky legislature designated the coffeetree as the state tree in 1976, but in 1994 they changed it back to the tulip poplar. Coffeetrees grow 60- to -75 feet and have a spread of 40- to -50 feet. The slow growing tree sprouts leaves that are 3- feet long and 2- feet wide. The leaves and pods produce litter, and like Bigleaf magnolias, coffeetrees are best suited for parks and woodlands.