A woody plant is any vascular plant that has a perennial woody stem -- that is, one that supports continued vegetative growth above ground from year to year. Many annuals appear to form woody stems in their first year, but nonetheless die back. A true woody stem contains wood, which is primarily composed of structured cellulose and lignin, and features a vascular, or circulatory, system. Most woody plants form new layers of woody tissue from year to year, each year over the layer of the preceding year, and so increase their stem diameter from year to year.
Woody plants are usually termed either trees, shrubs, or vines.