Plant toxicity is apparently a concern for many. A commenter on a recent GWI post voiced strong concerns about Ricinus communis (castor bean, a dramatic annual I’ve been thinking of growing this summer). Not wishing to cause the demise of any curious animals or small children—as darkly prophesied in the comment—I turned to my reference library to assess the danger, and, yes, Botanica confirms that ingesting the seeds could cause death in small children. It also recommends full sun and fertile soil.
Further investigation into plant toxicity reveals that digitalis (foxglove) is also among the most deadly plants grown in the landscape, while wisteria, clematis, boxwood, and azalea can all cause accelerated heartbeat, vomiting, skin rashes, or other virulent symptoms. Indeed, according to the Brooklyn Botanical Garden’s Desk Reference, there are at least forty commonly grown plants that can kill us, or at least make us very, very uncomfortable for a long period of time.
And therein lies the paradox. Clearly, most gardeners routinely grow poisonous plants. Some of them—like castor bean—are more rarely grown and thus have acquired more of a deadly mystique. I like the Desk Reference’s way of putting it: “Plants have not evolved to plague us … We humans are the intruders in their environments and we must find ways to coexist with them.”
The same book includes a cautionary list of common-sense strategies that help make sure plant poisoning never happens and then the usual advice on what to do if it does. The list is strongly reminiscent of the precautions families with children must follow to protect against the poisons in household cleaning substances.
I’m confident I can make sure no children eat any of my castor bean—or for that matter, my aconitum, colchicum, digitalis, or any of the other noxious cultivars I’ve been harboring. I’m not so sure I can stop passers-by from eating fallen horse chestnuts and thus incurring possible paralysis, or from going into convulsions after nibbling on any of the pokeweed that is rampant throughout our neighborhood. But I am almost positive of the unlikelihood of either of those events happening during my lifetime.
Plants have evolved certain strategies to ensure their survival in a hostile environment. So have humans—those are the ones that tend to concern me a bit more.