It is also among the most diverse with species growing nearly everywhere trees grow except the Northern Boreal Forest and the Tundra. There are about 60 species in North America north of Mexico. Oaks are usually easy to recognize because of their distinctive, elongate, lobed leaves and their acorns, a polished brown seed sitting in a shaggy cup.
Oaks occur in a wide variety of habitats.
Some species of the Eastern Deciduous Forest are large, stately trees occurring in forests with rich, moist soils. Others are specialized for dry conditions such as rocky or limestone soils. A few species are most commonly found along the margins or ponds, streams, and swamps. Outside of the Eastern Deciduous Forest, oaks grow along streams in the prairie, in the drier parts of the Montane Forests of the western United States, and are common in the dry mountain regions of the southwest. Oaks are also among the dominant trees of the Chaparral region of California.