Griffiths D., Illustrated Studies in the Genus Opuntia-III, Missouri Botanical Garden Annual Report, 1910, 21:165-174
The paper contains original descriptions of ten prickly pears from Texas, New Mexico and Mexico, based on field observations and plants propagated in cultivation. It characterises growth form, cladodes, areoles, spines, glochids, flowers and fruits, and identifies the origins of type material. The descriptions record colour changes and the accumulation of areolar structures as cladodes age.