I've read and been told that there are two, red and green. HOWEVER, Agri-Starts, the big tissue culture company where most of the nurseries get theirs from, only lists it as "Kru", not red or green. Theirs is red though.
AnnaJW has a plant labeled kru that looks green here:
http://www.bananas.org/gallery/showp...=500&ppuser=14
I've read JeffreyP once wrote that Red Kru can turn green by a shift in soil PH.