I sowed some czar beans in the spring all white seed, then last week we harvested the beans and were very surprised that one plant produced beans that are beautiful dark blue/black colour, the same size and shape as the czar’s. Can anyone explain what might have happened, do they cross (but the only black seeded beans we have are are climbing French beans) all the other runners we grow are are Gigantes, Firestorm and Streamline and Prizewinners and none of those beans are black. Will they be safe to eat? I hope so.