The Comps of Mexico is a long-running series of systematic accounts of all the tribes and genera of the family Asteraceae. Chapter 20 in this treatment deals with several subtribes, namely Montanoinae (genus Montanoa), Rojasianthinae (genus Rojasianthus), Rudbeckiinae (genera Ratibida and Rudbeckia), Spilanthinae (genera Acmella, Salmea, and Spilanthus), and Verbesininae in part (genera Podachaenium, Squamopappus, Tetrachyron, and Verbesina will be covered in Volume 24B)