alnus rhombifolia(n = noun.plant) mountain alder, white alder - tree of western United States;
is a kind of alder, alder tree
is a member of alnus, genus alnus

alnus, alnus crispa, alnus glutinosa, alnus incana, alnus maritima, alnus rubra, alnus rugosa, alnus serrulata, alnus veridis, alnus veridis crispa, alnus vulgaris, genus alnus, sida rhombifolia