Black Oak Savanna is a xeric ecotype recognized as a grove of widely spaced black oaks interspersed with a low growth of sun loving, fire tolerant grasses, shrubs, forbs, and sedges. In an old grove the dominant trees are of mixed ages, and the shrub zone is quite sparse. One distinctive and pleasant aspect of a savanna is that due to the relatively sunny conditions, forbs bloom throughout the growing season, unlike the forest where the gloom of summer descends by June and flowering ends until spring.
Like a sand prairie, a black oak savanna develops on sandy soil, especially the Plainfied and Coloma sands. It is commonly said that the savanna contains prairie species plus scattered oak trees. This is true as far as it goes, and their is no questioning the prairie affinities of an oak savanna, but to an extent the image of a savanna as a prairie with trees is misleading, because the savanna contains species especially adapted to its unique conditions--hyperdrainage, broken shade and frequent hot fires. While there are many species that thrive in both prairie and savanna, many others are only found in one or the other.