Columbia subject headings:
Harvard subject headings:
Hydromorphic soils--Identification--Handbooks, manuals, etc.
Wetland plants--Maryland--Identification--Handbooks, manuals, etc.
Wetlands--Identification--Handbooks, manuals, etc.
Princeton subject headings:
Wetland plants--Canada--Identification.
Wetland plants--United States--Identification.
Wetlands--Canada--Identification.
Wetlands--United States--Identification.