The cucumber tree has a pyramidal crown when young, developing a rounded, spreading crown at maturity, with large, wide-spreading branches. Upper branches ascend and lower ones arch down to the ground. Trees can live to 150 years and grow to a height of 100 feet, with an 80-foot spread. Fall color is brown or ashy-gray.
Flowers are solitary, appearing after the leaves in late spring.
The fruit is a leathery, cylindrical aggregate of pinkish follicles up to 3 inches long, produced in October. The structure looks somewhat like a miniature cucumber. The seeds are bright red and are suspended on thin, white threads after being released. The terminal buds are enclosed in a single scale which is covered with numerous long, silky, silver hairs. Leaf scars are U-shaped, with 5 to 9 bundles scars.