Vernal ponds are wetlands that are dry part of the year; they can have many kinds of vegetation. Prairie potholes are depressed wetlands that fill up with rain or melted snow; they are located primarily in the Upper Midwest.

California Vernal Ponds
California Vernal Ponds, California Chaparral Institute, Article with several photographs.
Prairie Pothole and Marsh Wetlands
Prairie Pothole and Marsh Wetlands, Texas Coastal Wetlands, What's the difference between a prairie pothole and marsh wetland? Find out here.
Prairie Potholes
Prairie Potholes, U.S. Environmental Protection Agency, A combination of text and photographs.
Vernal Pond - Camp Naturalist
Vernal Pond - Camp Naturalist Wood & Western Chorus Frogs Calling - April 7, 2008 Please visit the website to view photographs,
Vernal pond Video
Vernal pond, YouTube.com, Video length: 0:24.