Using categorical predictors in regression tress

I was wondering if it is possible to use categorical predictors in regression trees.

For example, when considering the "carsmall" example on the Mathworks website it provides

tree = fitrtree([Weight, Cylinders],MPG,'categoricalpredictors',2,'MinParentSize',20,'PredictorNames',{'W','C'})

Where "Weight" and "Cylinders" are both matrices. However, using

tree = fitrtree([Weight, Model],MPG,'categoricalpredictors',2,'MinParentSize',20,'PredictorNames',{'W','M'})

doesn't work as "Model" is a character array.

Is there a way to use word (char or string) categorical predictors using fitrtree or fitctree? Or should I be using something else?