Canvasback

The canvasback (Aythya valisineria) is a species of diving duck, the largest found in North America.

==Taxonomy== Scottish-American naturalist Alexander Wilson described the canvasback in 1814. The genus name is derived from Greek aithuia, an unidentified seabird mentioned by authors, including Hesychius and Aristotle. The species name valisineria comes from the wild celery Vallisneria americana, whose winter buds and rhizomes are the canvasback's preferred food during the nonbreeding period. The celery genus is itself named for seventeenth century Italian botanist Antonio Vallisneri.