The GREEN PILLAR® pin oak is notable for its tall narrow habit, as its name implies. Like other pin oaks, it will tolerate swampy soil but not alkaline soil. A member of the red oak group, the pin oaks produce acorns biennially. This cultivar was introduced in 1995.

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.