Q: I want to grow the huge, gorgeous red-leafed plants I've seen on my neighbors' stoops. But I've been told they are ricinus, the plant that was used to assassinate the Bulgarian dissident Georgi I. Markov, back in 1978. Please tell me this is not the same ricinus but only a harmless cousin.
A: Ricinus, aka castor bean, is cousin-free. There is only one species, Ricinus communis. The ricin it contains, primarily in the seed coat, is among the deadliest poisons known. And like many plants in the spurge (Euphorbia) family, it can cause rashes in those who are sensitive to it.
But if castor beans are far from harmless, they are also far from alone. Consider popular spurges like the houseplant crown of thorns, and toxic garden beauties like larkspur, daphne and rhododendron.
In other words, castor beans are fine to grow as long as you do not eat them and are careful to keep children away from the attractive mottled seeds. For safety, plants in public places, including front stoops, should have their bright red seedpods removed. As you may have noticed, nobody does this. Yet accidental poisonings are rare.
Your neighbors probably grow Carmencita, the most common red-tinged castor bean, but if the leaves have a metallic shine they may be New Zealand Purple. Both can reach 8 feet tall in one season, so even single plants are show-stoppers.
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If size matters most, go for the green version, Zanzibariensis, a 10- to 12-footer with 3-foot-wide leaves, though like all castor beans, it will be just a brown corpse after the first fall frost.
Sources include J.L. Hudson, Seedsman, or jlhudson
seeds.net, and Diane's Flower Seeds, (801)782-8121 or dianeseeds.com.
Address questions by e-mail to gardening@nytimes.com . Unpublished questions cannot be answered individ-ually.
