Mauseth and Plemons have hypothesized that seven lines of evolution exist for Cactoideae wood.
Characterization of secondary phloem in members of Cactoideae is scarce (Mauseth & Ross, 1988: Loza.
In all of the Cactoideae that we studied, the periderm originates from epidermal cells and develops late in most species, beginning as patches at the base of the stem (Mauseth & Ross, 1988; Mauseth et al.
One of the interesting results of these phylogenetic analyses based on structural characters is our finding that the subfamily Cactoideae is a supported clade (b74/j66% and b60/j55%), recovered as monophyletic in both analyses, based on the presence of highly reduced leaves (character 8), interpreted as the synapomorphy for the clade.
The other morphological characters mentioned by Anderson-the presence of caepitose, unsegmented globose stems (5), of an undifferentiated fertile zone (15), flowers open during the day (29), and a naked pericarpel (25)-have also appeared independently in other Cactoideae taxa.
All of these features evolved independently in other taxa of Cactoideae.
This genus is recovered as basal to the whole Cactoideae (Fig.