Castor bean (Ricinus communis)

One autumn morning in 1978, communist defector and BBC journalist Georgi Markov walked across London’s Waterloo Bridge and stood waiting at a bus stop.  He felt a painful jab in the back of his thigh and turned around in time to see a man pick up an umbrella, mumble an apology, and run away.  Over the next few days, he developed a fever, had trouble speaking, began throwing up blood, and finally went to the hospital, where he died.

The pathologist found hemorrhages in almost every organ in his body.  He also found a small puncture mark on Markov’s thigh and a tiny metal pellet in his leg.  The pellet contained ricin, the poisonous extract of the castor bean plant. Although KGB agents were suspected of the crime, no one has ever been charged with the infamous “umbrella murder.”

Castor bean is a dramatic annual or tender perennial shrub with deeply lobed leaves, prickly seed pods, and large, speckled seeds.  Some of the more popular garden varieties sport red stems and splashes of burgundy on the leaves.  The plant can reach over ten feet tall in a single growing season, and will grow into a substantial bush if it is not killed by a winter freeze. Only the seeds are poisonous. Three or four of them can kill a person, although people do survive castor seed poisoning, either because the seeds aren’t well chewed, or because they purge them quickly.

Castor oil has been a popular home remedy for a variety of ailments for centuries. (The ricin is removed during the manufacturing process.)  A spoonful of the oil is an effective laxative. Castor oil packs are used externally to soothe sore muscles and inflammation. It’s also used as an industrial lubricant and in cosmetics and other products.

But even this natural vegetable oil is not entirely benign — in the 1920s, Mussolini’s thugs used to round up dissidents and pour castor oil down their throats, inflicting a nasty case of diarrhea on them.  Sherwood Anderson described the castor oil torture this way: “It was amusing to see Fascisti, wearing black shirts and looking very earnest, bottles sticking out of their hip pockets, chasing wildly down the street after a shrieking Communist.  Then the capture, the terrible assault, hurling the luckless Red to the sidewalk, injecting the bottle into his mouth to the muffled accompaniment of blasphemy of all the gods and devils in the universe.”

Family:  Euphorbiaceae

Habitat:  Warm, mild-winter climates, rich soil, sunny areas

Native to:  Eastern Africa, parts of western Asia

Common names:  Castor bean, palma Christi, ricin

Meet the relatives: The garden spurge called euphorbia, known for its irritating sap; the poinsettia, also mildly irritating but, contrary to rumor, not dangerous; and the rubber tree, Hevea brasiliensis, source of natural rubber.

Excerpted from the New York Times bestseller Wicked Plants by Amy Stewart. For more example of plants behaving badly, check out the author video below. And stay tuned tomorrow for the very first installment of Amy Stewart’s delicious new column, Dr. Bleedingheart! Plus, don’t forget you can enter to win a copy of this book along with two other Halloween-spirited titles all this week; details here.

-christina