Petunia \Pe*tu"ni*a\, n. [NL., fr. Braz. petun tobacco.] (Bot.) A genus of solanaceous herbs with funnelform or salver-shaped corollas. Two species are common in cultivation, {Petunia violacera}, with reddish purple flowers, and {P. nyctaginiflora}, with white flowers. There are also many hybrid forms with variegated corollas.