Trees, Shrubs and Woody Vines
Black hickory's nut, like that of the pignut hickory, is awfully hard to crack. Because rural Ozarkers noticed their hogs had no trouble extracting the sweet kernels, both species came to be called "pignut hickories."
About Trees, Shrubs and Woody Vines in Missouri
There are no sharp dividing lines between trees, shrubs, and woody vines, or even between woody and nonwoody plants. “Wood” is a type of tissue made of cellulose and lignin that many plants develop as they mature — whether they are “woody” or not. Trees are woody plants over 13 feet tall with a single trunk. Shrubs are less than 13 feet tall, with multiple stems. Vines require support or else sprawl over the ground.