Dave's Garden. Search the extensive PlantFiles database.
Links for Opuntia pusilla
Carolina Nature - Illustrated woody plant profile, with notes on range and identification. (1 photo)
Lady Bird Johnson Wildflower Center - Plant description and characteristics with notes on distribution, culture, and propagation. (3 photos)
Opuntia Web: Opuntia pusilla (O. drummondii) - Enthusiast's page describes characteristics and natural habitats of the species (and its subspecies, where appropriate). (27 photos)