Which department does a professor in a joint appointment get his/her graduate students from

If someone is a professor of department A, however, s/he also affiliates with department B in a joint appointment. Which department does the professor in a joint appointment get his/her graduate students from? Department A or B? The original or affiliated department? Also, does he/she evaluates the admission of A or B? Or both? Thank you. I did a web search on this site with the keyword joint appointment, but I can not find any similar discuss.