The Lilioideae are a subfamily of monocotyledonous perennial, herbaceous mainly bulbous flowering plants in the lily family, Liliaceae. They are found predominantly in the temperate and colder regions of the Northern Hemisphere, particularly East Asia and North America. The subfamily includes two tribes. They are of economic importance, particularly the lilies and tulips.

Tulips are spring-blooming perennial herbaceous bulbiferous geophytes in the Tulipa genus. Their flowers are usually large, showy, and brightly coloured, generally red, orange, pink, yellow, or white. They often have a different coloured blotch at the base of the tepals, internally. Because of a degree of variability within the populations and a long history of cultivation, classification has been complex and controversial. The tulip is a member of the lily family, Liliaceae, along with 14 other genera, where it is most closely related to Amana, Erythronium, and Gagea in the tribe Lilieae.