Evolution of habit in Cactaceae is of much recent interest, especially with regard to leaf form and below ground storage. Recent study of Opuntioideae provides a phylogenetic framework for considering morphological evolution in that subfamily. Four main lineages exist within the Opuntioideae. The deepest lineage consists of early deciduous, globular-stemmed, diminutive, often geophytic plants (Maihueniopsis). The second deepest lineage consists of early deciduous, globular- or cylindricalstemmed geophytes (Pterocactus). Persistent leaves are a derived, iterative character state in Opuntioideae. Diversity in Opuntioid morphological features (below ground storage organs, stem shape, and leaf persistence) in the phylogenetic context shows a trend towards increased size and surface area. Parsimonious reconstruction of ancestral character states suggests that early Opuntioideae may have been diminutive, early-deciduous, possibly geophytic plants. The polyphyletic genera Maihueniopsis and Puna (= Maihueniopsis s.l.) possess many characters plesiomorphic for Opuntioideae.