The USNVC Hierarchy Explorer provides detailed descriptions of vegetation types in the U.S. USNVC Version 2.04 is the June, 2022 release of the classification. The USNVC is still under development for some geographies for details see Status of USNVC Vegetation Hierarchy.
General Citation for USNVC 2.04:
USNVC (United States National Vegetation Classification) Database [Version]. [Year] Federal Geographic Data Committee, Vegetation Subcommittee. Washington D.C. Date Month Year Accessed.