Opuntioideae

Opuntioideae is a subfamily of the cactus family Cactaceae. This subfamily is characterized by its flattened, stem segments called cladodes or pads, although some genera within the subfamily have cylindrical stems. Opuntioideae is a diverse group, encompassing a wide range of species adapted to various arid and semi-arid environments. The subfamily is primarily found in the Americas, with its center of diversity in Mexico and the southwestern United States.

Key features of Opuntioideae include the presence of glochids, which are small, barbed bristles that grow in areoles, the specialized structures from which spines and flowers emerge. These glochids are easily detached and can be irritating to the skin. The flowers of Opuntioideae are typically large and showy, often yellow, orange, pink, or red, and usually solitary or in small clusters. Following pollination, these flowers develop into fleshy fruits, commonly known as prickly pears or tunas, which are edible and have been a food source for humans and animals for centuries.

The subfamily is divided into several tribes, with the most prominent being Opuntieae. Genera such as Opuntia, Cylindropuntia (chollas), and Grusonia are well-known members of this subfamily. Opuntia is perhaps the most recognized genus, distinguished by its flattened, paddle-like cladodes. Cylindropuntia, on the other hand, features more cylindrical or segmented stems and often has exceptionally long and sharp spines. The ecological roles of Opuntioideae are significant, providing habitat and food for various desert wildlife, and their adaptations to arid conditions make them important subjects of study in plant physiology and evolutionary biology.