Pectin-methylesterase family tree. Two large polytomies, labeled “A” and “B” and shown in light grey, indicate poor resolution of some of this family’s lineages. Four monophyletic clades contain members from the monocots, eudicots, Selaginella, and Physcomitrella. One of these clades (blue cloud) consists of polytomy B and a smaller clade of Physcomitrella and Selaginella genes. Additional moss and tracheophyte genes remain poorly resolved in polytomy A. The algal root (from P. margaritaceum) is within one of the polytomies.