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If you are suffering from allergies, tree and plant pollen may be the reason.


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The Terrorist's Favorite Weed: Castor Bean

The Castor bean plant (Ricinus communis) with its large bold, highly colored leaves is native to tropical Africa. In cold climates it is an annual, growing quickly, setting many seeds, and dying off in winter. In mild winter areas it is a long-lived perennial, sometimes reaching small tree size. It has gone wild and naturalized in many places and is especially common in coastal areas. Each plant produces hundreds of the bean-like seeds and these seeds can remain viable for more than a decade.

Castor bean is a Euphorbia (Spurge) family member and like many Euphorbias it is poisonous, has highly caustic sap, and produces extremely allergenic pollen.

Before World War Two castor bean was not common in the US, grown mostly as an unusual foliage plant in a few gardens. But during the war there was a need for castor oil and the government encouraged farmers in the Midwest to start growing large acreage of it as an oil seed crop. The first year it was grown not much happened but by the end of the second season huge numbers of people living near the castor bean fields started getting hay fever and asthma. Castor bean pollen is an abundant and potent allergen.

There is another more sinister use for castor bean. The mottled seeds of castor bean, which are about the size and shape of large pinto beans, contain two powerful poisons, the alkaloid ricinin and the toxalbumin ricin.

Ricin, a white protein powder is a remarkably deadly cytotoxin. The poison in the seeds is so strong that eating a single seed can kill a child. Animals, horses in particular, that eat the succulent leaves die from ricin poisoning. Ricin is even more toxic than strychnine and cyanides. Ricin also has the ability to accumulate in the body until a lethal dose is reached. Symptoms of ricin poisoning are stomachache, headache, fever, nausea and vomiting, bloody diarrhea, cold sweat, sleepiness, disorientation, shortage of breath, seizures, and death.

Terrorists have long been enamored of castor bean and ricin. Modern day mad scientists can extract ricin from castor bean seeds. Just how poisonous is ricin? Ricin is one of the most poisonous naturally occurring substances known to man. As little as one milligram of ricin can kill an adult.


Georgi Markov was a Bulgarian journalist who had spoken out against the Bulgarian government. While waiting for a bus near Waterloo Station in London, in 1978, Markov was murdered, stabbed in the leg with a poisoned umbrella. A perforated metallic pellet stuck in his leg was found to contain the deadly ricin toxin.

More recently it has been widely reported that Thomas C. Leahy, known by his neighbors as the “Mad Scientist,” was producing ricin in his Wisconsin basement. Leahy, a high school dropout and self-taught chemist, had also tried to grow anthrax. Ricin if inhaled or even touched can kill in a day or two. Luckily for us, Leahy is now serving seven years in state prison for shooting and wounding his 13-year-old stepson.

Going Native

Castor bean plant spreads quickly because it has many built-in advantages over native plants. A very robust grower, its leaves are poisonous even to predatory insects. Aphids that can safely feed on many other poisonous plants quickly die after sucking the juice of castor bean leaves.

But castor bean has one disadvantage. It is completely easy to recognize and can then be killed by chopping it down or spraying it with herbicides.  I have long advocated eradication of castor bean because it causes so many allergies. It would be wise to realize too, that not only is castor bean pollen allergenic, but it is also poisonous pollen. Exactly what the effects of breathing in poisonous pollen are we don’t know, but it cannot be good.

Given the deadly potential of this all too common weed for bio-terrorists, perhaps it is time we have our state and federal marijuana hunting exterminators, shift gears and change targets. They won’t have to look hard. In California Ricinus communis can be found growing lushly all along Highway 101.

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