pomato
/pəˈmɑːtəʊ/noun
A graft hybrid produced initially by Luther Burbank (1849–1926), U.S. horticulturist, by grafting tomato scions on to potato roots; the edible fruit of such a plant, resembling a white-fleshed tomato. Also: any of certain other apparent hybrids between the potato and the tomato, e.g. one produced by fusing potato and tomato cells.
Origin
Early 20th century; earliest use found in The Century Illustrated Monthly Magazine. Blend of potato + tomato.