An oak savanna is a type of savanna—or lightly forested grassland—where oaks are the dominant trees. The terms "oakery" or "woodlands" are also used commonly, though the former is more prevalent when referencing the Mediterranean area. These savannas were maintained historically through wildfires set by lightning, humans, grazing, low precipitation, and/or poor soil.

Darien is a city in DuPage County, Illinois, United States. Per the 2020 census, the population was 22,011. A southwestern suburb of Chicago, Darien was named after the town of Darien, Connecticut. Darien is just north of I-55 and Historic U.S. Route 66. The entire south edge of the town borders Waterfall Glen.