Prickly Pear

There are many species of Prickly Pear in their native Americas but those which have been dispersed around the world are generally referred to as the Opuntia ficus-indica species though I am not sure that is the case for all of them. <br> Quite why some plants have different coloured fruit, especially where they grow wild, I don't know. See pictures 3 & 4 where just a single plant has all yellow fruit whilst all the others have reddish fruit.