library(MplusTrees)

script = mplusObject(
  TITLE = "MplusTree;",
  MODEL = "b0 b1 | wt12@0 wt13@1 wt14@2 wt15@3 wt16@4;",
  usevariables = c('wt12','wt13','wt14','wt15','wt16'),
  rdata = data)

fit = MplusTrees(script, data, group=~id,
                 rPartFormula=~sex+race+momed, catvars=c("race"), 
                 control=rpart.control(minsplit=200, minbucket=200, cp=.00019))

fit
plot(fit)