The black oak gets its common name from the deep brown to almost black color of its bark at maturity although the inner bark is yellowish orange and was once used as a source of yellow dye. It produces acorns biennially after up to 20 years of growth. Rarely seen in commerce, the black oak can be found in dry uplands but does best in richer, moister soils.

The genus Quercus includes more than 600 species of the oak tree, of which 90 are native to North America; the Chicago Botanic Garden's collection contains more than 60 varieties and over 1,000 individual trees. Twenty oak species are native to Illinois.

Oaks are slow growing, long lived, hard wood trees that produce fruit we all know as acorns. Within the white oak group, acorns mature annually; in the red oak group, acorns take two years to mature (biennial). Oaks are often imposing shade trees at maturity and provide habitat and food for a variety of wildlife.