Opuntia arenaria—Areoles and Glochids on Roots

Areoles on roots of Opuntia arenaria contain both trichomes and glochids. These root areoles erupt intact through a periderm. New shoots may arise from root-bearing areoles of O. arenaria either before or after the areoles have erupted through periderms and may do so while the root is either attached or detached from its original shoot and while the root is either above or below ground. Opuntia arenaria roots are unusual for a cactus in being highly mucilaginous, much like their shoots.