Fens are peatlands with wet, spongy ground. They are commonly dominated by sedges. They are formed in poorly drained areas and have a higher pH than bogs, being somewhat acidic to alkaline, and are also more nutrient rich. These wetlands frequently surround open bodies of water and are usually located in regions of the northeast, the northern plains and Canada. They commonly have rather diverse and interesting flora, including many rare species.
Vernal pools are wetlands found in inland areas, particularly in California.
They are wet during the winter and early spring, have a herbaceous aspect and support a number of rare plant species. These wetlands are characteristically shallow, bowl-shaped depressions in gentle rolling plains. Some resemble prairie potholes. Occasionally, this inland wetland becomes a shallow lake. Cypress-gum swamps are wetlands usually found in the South.