Loza-Cornejo S., Terrazas T., Epidermal and hypodermal characteristics in North American Cactoideae (Cactaceae), Journal of Plant Research, 2003, 116(1):27-35, doi: 10.1007/s10265-002-0066-2
The epidermis and hypodermis study of North American Cactoideae includes Ariocarpus fissuratus and A. retusus. It compares microscopic surface structure and considers the cuticle's protective role.