Cladrastis kentukea - Yellowwood
Family - Fabaceae
Size - 30 to 50 feet in height with a spread of 40 to 55 feet. Can be somewhat slow growing in the South, maybe a little over a foot per year. Trees on campus are approximately 20 feet tall, and were planted as 1.5 to 2 inch caliper trees in 1989.
Leaf - Alternate, odd-pinnately compound. Bright green in Spring, good yellow fall color.
Flower - Can be extraordinary in flower. Seems to have alternately better years than other years. White, fragrant, approximately 1 foot long panicles born on the terminal ends of the branches. Flowers approximately mid-June in North Alabama. Slow to begin flowering. Our trees were in the ground for 9-10 years before they began to flower. Michael Dirr says they begin to flower at 12 to 18 feet tall, so this would equate with the age.
Bark - Very Beech-like in appearance. Smooth, gray, and mottled.
Problems - none after 13 to 14 years
Landscape Use - Can be a nice tree for home use or the commercial site. It isn't messy, but the only real problem really associated with this tree one needs to consider is that it can have sharp crotch angles which can lead to large branches splitting away from the trunk as it gets larger. Some of the crotch angles are deep where limbs attach to the tree, forming U shaped cups and hold water that most certainly can lead further to decay in the location where the branch is attached. Has poor branch collar formation. One needs to train the branch structure early to be more open, with horizontal and wider spaced branches so that it can live a reasonable lifespan. Seems to hold up quite well to extremes of heat and drought so there could be use as a parking lot tree with proper pruning early in life.
Performance - 7- Can be slow to flower, and it's flowering is not consistent from year to year. The branching structure can present some real problems down the road reducing the lifespan of the tree.