swan: stately heavy-bodied aquatic bird with very long neck and usually white plumage as adult
aquatic bird: wading and swimming and diving birds of either fresh or salt water
dilleniidae: a group of families of more or less advanced trees and shrubs and herbs having either polypetalous or gamopetalous corollas and often with ovules attached to the walls of the ovary; contains 69 families including Ericaceae and Cruciferae and Malvaceae; sometimes classified as a superorder