Description: English: Robert H. Mohlenbrock. USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. Courtesy of USDA NRCS Wetland Science Institute. Date: 1995. Source: http://plants.usda.gov/java/largeImage?imageID=diov_001_avp.tif. Author: Robert H. Mohlenbrock. USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Northeast National Technical Center, Chester. Courtesy of USDA NRCS Wetland Science Institute.