Castor bean plants are beautiful. They have vibrant, red leaves and they produce red and yellow flowers. They're also extremely toxic to both people and animals. Like red kidney beans, castor beans contain high concentrations of a particularly harmful lectin. The lectin in castor beans is called ricin.
Yep, the ricin in castor beans is the same poison that Jesse helped Walter White cook up in "Breaking Bad." It's actually very easy to distill ricin from castor beans, and a terrorist tried to poison President Obama and U.S. Senator Roger Wicker with envelopes of the stuff in 2013 [source: Nosowitz].
Even cooking castor beans isn't enough to destroy ricin. In fact, you make the poison using the mash leftover from processing castor beans for their oil [source: CDC]. Castor oil is the only castor bean product that's safe to eat; since ricin is water soluble, it doesn't end up in processed castor oil, as long as the processing was done properly [source: Cornell].