Question
We found a purple butterbean at an old flea market.The vines,leaves,flowers and the butterbean hulls are a dark purple.The plant had run up a light pole about 12 feet and was loaded with beans,dont know what color beans are when not dry but when dry they are small and black with a little white on one edge.No one knows if you can eat the beans or not.This is not the purple string bean!

Answer
go to site www.botany.com/phaselous to see which one you speak of. type purple butterbean into your search engine. they are closely related to lima and snap pole beans. you can ID them from their bean color, stems, & foliage. purple seed ones are phaseolus lunatus. don't eat it until you research it more. castor beans are the only seed registered as poisonous. most others if harmful will give you an upset stomach and diarrehea.