library(partykit)
library(rpart)

result1 <- rpart(Species~.,data = iris)
plot(as.party(result1))

rpart_party <- function(formula, data){
  result1 <- rpart(formula = formula ,data = data)
  return(as.party(result1))
}
plot(rpart_party(Species~., data = iris))

Error in eval(predvars, data, env) :
  invalid 'envir' argument of type 'closure'

rpart_party <- function(formula, data){
  result1 <- rpart(formula = substitute(formula), data = data)
  return(as.party(result1))
}