1. the mean age of the trees constituting a forest, crop, or stand —note in practice, in even-aged forests, the mean age of dominant and sometimes also codominant trees is taken, and the age of a plantation is generally taken, from the year in which it was formed, i.e., exclusive of the age of the nursery stock then brought to it 2. of a tree, the time elapsed since germination of the seed or the budding of, e.g., the sprout or cutting from which it developed —see effective age This definition last updated 10/23/2008