The classification of the dwarf Andean opuntias has long fascinated James Iliff. In Studies in the Opuntioideae (Cactaceae), devoted to an important group of cacti – the subfamily Opuntioideae – whose classification has been somewhat neglected compared with their cousins in the rest of the cactus family, Iliff's annotated checklist is complemented by ground-breaking papers on aspects of the classification and evolution of the subfamily as a whole and on its representatives in other parts of its wide natural range in North and South America.
- Systematic implications of chloroplast DNA sequence variation in the Opuntioideae (Wallace & Dickie)
- Seed characters and the classification of the Opuntioideae (Stuppy)
- On the evolution of the North American Opuntioideae (Pinkava)
- Realignment and revision of the Opuntioideae of Eastern Brazil (Taylor, Stuppy & Barthlott)
- The Andean opuntias: An annotated checklist of the indigenous non-platyopuntioid opuntias of South America (Iliff)
- That's Opuntia, that was! (Hunt)
- Alphabetical list of currently accepted species (Hunt)