Frog Lake and Pines State Natural Area contains a red and white pine forest situated between Frog Lake and the Manitowish River. The pines are in a medium-age class, the red pines to 2 feet in diameter at breast height and some white pines even larger. Other trees include white birch, aspen, red maple, and balsam fir. The largest pine timber lies south of the east-west woods road and closest to Frog Lake. White pine reproduction is more common southward.
Reproduction is most evident where disturbance has occurred or communities meet.
North and east of the lake red pine occurs on soils with 1-3 inches of duff and organics over sandy loam. Frog Lake is a deep, soft, seepage lake with a sandy bottom overlain with muck in many areas. The lake is 45 feet deep with a Secchi disk reading of 8 feet. Submergent aquatics are dense and include bladderwort, Robbin's spike rush, watershield, white and yellow pond lilies, and pondweeds. Group Use, Research Use, Individual Nature Study, Hunting, Fishing, Boating or Canoeing.