Inland of the coastal marshes and prairies, there was typically a broad band of lowland forest. Lowland conifer swamps, dominated by tamarack often occurred in broad depressions within the sand lake plain, especially where these depressions were located 1 or more miles inland from the present shoreline. Flat, inland expanses of sand lake plain supported eastern hemlock, with some white pine as well as black ash, elm, and other hardwoods. There were also hemlock-dominated areas described by the GLO surveyors as swamp. On the flat sand lake plain, a few inches of elevation often results in changes of drainage class, making it difficult to determine whether an area should be called upland or wetland.
Flooding is common in both spring and autumn.
On the better drained portions of the clay plain at the southern end of Saginaw Bay, forests were dominated by beech and sugar maple. These three lowland hardwood species dominated large expanses of the clay plain, but tamarack and northern white-cedar were also present in the swamps. The flat conditions of the clay lake plain resulted in an intergrading of upland and wetland hardwoods on the landscape. Forests on fine-textured till plain were similar to those found on the clay lake plain. In the north, forests dominated by hemlock were common on the clay lake plain.