This is a widespread variable species in eastern states, most common on base-rich soils in the midwest. In Ky. altissimum is most abundant on calcareous soils, but it does occur locally on non-calcareous soils or highly leached calcareous soils. Chromosome numbers deserve further investigation; 2n = 20, 30 and 40 across its range. Also hybrids with serotinum and hyssopifolium can be expected (FNA 21, Y). The species is sometimes confused with album with only vegetative material. Leaves of altissimum differ from those of typical album as follows: L/W mostly 5-10 (versus 3-4); strongly 3-nerved from base (versus pinnately nerved to weakly 3-nerved, not with strong basal division); margins proximally entire, distally serrate (versus all coarsely serrate); apices acuminate (versus obtuse to acute).