Castor Bean – Ricinis communis.  Folks who make their living creating fabulous color displays for public gardens, municipalities, and commercial parks love ‘em.  Civilian gardeners/plant geeks love ‘em.  People who get their knickers in a twist about poisonous plants do not.

Pros:  ridiculously rapid growth, huge leaves for that tropical look, tolerant of less-than-ideal conditions, cheap and easy to grow from seed, weird wild flowers and seed pods.

Cons: pretty darn poisonous. A few seeds (have seen figures from four to 20), chewed up to release the toxic protein ricin, will allegedly kill you. A Caster Bean seed looks like a really huge tick (head and all), which should be sufficiently repellent to anyone over ten years old. Pleh.

Beans with flowers. U.S. Botanic Garden, 2005, Washington D.C.

This topic arises because I was standing in our campus garden yesterday with said pot o’ poison (cultivar ‘Carmencita’, a red-leaf form), trying to find a place to plant it.  Last summer, my department head noted them growing in front of our garden pavilion and asked that I kindly remove them. “They’re really poisonous, and kids will stick anything in their mouth, and I wouldn’t want my kids around them” (quoted best of my memory). He’s a wonderfully laid-back guy, so it struck me that he must really be concerned to bring it up.  I teach Castor Bean in my Herbaceous Landscape Plants class for both the pros and the cons…heaven forbid a Hort graduate is unable to identify it, so I persuaded him into letting me keep it up if I removed the seed pods before they ripen. I’m not going to go into all the medicinal/industrial uses of castor oil (ick…I hope my generation was the last to have this foisted on us) nor the insidious uses of ricin – Google away if you’re interested.

We temperate-zone gardeners love anything tall and big-leaved to give vertical “oompf” to summer beds and container plantings. The tropical African native is considered an invasive plant throughout the subtropics; I’ve seen it in pastures and fence rows in far south Florida, the Cayman Islands and Dominican Republic.  Apparently the cows and goats have learned to avoid it (natural selection?). I noticed it used en masse in the gorgeous beds lining the street in downtown St. Louis last summer, as well at several other public gardens I’ve visited over the past few years. So I’ll continue to use it in our garden’s palette of plants, but will remove the pods to keep everybody happy. 

p.s. At the top of my summer reading list is Amy Stewart’s book “Wicked Plants”. 

15 thoughts on “Beantroversy”

  1. I’m one of those that gets their knickers in a twist about poisonous plants, but not about their use – about their inconsistent exclusion. How is it that Ricinus gets the boot, but Taxus, Lantana, Aconitum, Digitalis, Narcissus, Colchicum, Nerium, Capsicum, and on, and on, and on…are perfectly fine??? If the powers that be are going to exclude poisonous plants because a child, idiot, or drunk may eat them, at least they should be even handed in their efforts. Take away everything that’s poisonous, sharp, and hot too. And not just from your public places, get that stuff out of your home as well lest a child, idiot, or drunk be there too – you can never be too careful. And let’s ban television and fatty foods while we’re at it.

    It would be interesting to see how many deaths were confirmed in areas where the plant is native or has naturalized.

    Banning Ricinus seems like a small thing (and yes, I understand you came to a compromise – but I wanted those seeds!) but banning a plant because it’s poisonous without banning other poisonous plants seems like heavy-handed and poorly reasoned.

    And I’d like to float the idea that possibly people should pay more attention to what their kids are eating.

    So there.

    1. Yahoo! A well thought out, well reasoned comment. I too, have wondered about this beautiful plant being “the bad guy” when there are so many house plants and garden plants commonly grown that are toxic. If you want to grow this wildly beautiful plant, plant a “specimen” and cut off the flowers! Enjoy!

    2. The question is basically, how often and easily does it kill people?

      The answers vary. Most of those things simply don’t kill people who aren’t trying to make some kind of herbal brew, either because they are suicidal, idiots, or can’t tell the difference between poisonous and non-poisonous plants. Digitalis, for instance, is incredibly poisonous, but I was unable to find a single substantiated case of accidental ingestion not from making an herbal tea leading to death. I was able to find ONE case of a small child ingesting it that would have been fatal if there wasn’t medical intervention, but in the sum total of medical literature, that puts it on the “safe” list to me. Why? Because it apparently tastes absolutely foul. The vast, vast majority of potentially deadly plants are similar.

      There are three plants that DO kill children, though, and they are forbidden from my yard and should not be placed where children have access if you’re a responsible person. Those are aconitum, oleander, and, yes, the castor bean plant. Poke berry is a wild plant that’s similarly banned. (The berries actually taste sweet and encourage children to eat them.)

      No, he wasn’t overreacting or being inconsistent. There are just three plants in the nursery trade that pose a substantial risk for truly accidental poisoning, and castor bean is one. Just knowing a list of poisonous plants isn’t enough. You have to be fully educated as to the real risks (or non-risks) of a plant. A little knowledge (oh, but daffodils are poisonous, too!) is a very, very dangerous thing.

  2. PW, can I just cut and paste that into my post? Because that’s what I really wanted to say about the whole situation.

    We went through the same thing with Datura metel a few years ago – it upset one of our volunteers that we would have it in the color beds…

  3. Ditto the first comment. And: a child old enough to be running around a garden unsupervised is old enough to understand, “Don’t put stuff you don’t know what is in your mouth.”

    1. I know a family who lost a child to oleander poisoning. The child was not unsupervised. She was standing right next to adults next to a bed of oleander in a public planting and grabbed a leaf and ate it. The adults saw her and tried to stop her, but she was too fast. She died. But I guess shame on those adults, who didn’t know that oleander was a deadly poison until their kid was in the hospital, dying.

  4. You’ll love “Wicked Plants”, and I so agree with you and Paul. Add very common weeds and wildflowers like, poison hemlock, white snakeroot, and larkspur to the list. What about mushrooms? Spoiler alert (although you probably know this).
    P.S. Apparently, she’s working on a follow up – Wicked Bugs.

  5. Welcome to the litiginous real world. People are so eager to sue anyone for anything that I’m not surprised your chair was worried. People fail to understand that plants don’t like to be eaten and have some pretty amazing ways to thwart herbivory. (An aside – the most incredible class I ever took during my graduate career was Plant Biochemistry. Find Robinson’s “Organic Constitutents of Higher Plants” (I think the 6th edition is the last) Amazing. Unfortunately it’s a bit dated, but still…amazing.)

  6. Castor bean is a noxious weed in my part of the world. I spend too much time pulling it up to appreciate its beauty. It’s a pity too, because big-leaved drought-tolerant plants aren’t that common.

  7. Matilija – How concerned are you (and others where you live) as to the poisonous aspects? Or is weediness a greater concern?

  8. How do you teach deer to eat castor bean? Any ideas? It would be a great way to ‘naturally’ decrease the surplus population in the northeast. But … rethinking … deer have nibbled on my narcissi without obvious declines in herd numbers, and they nibble mountain laurel when they’re really hungry and still come back for more. Golly it would be great to learn that castor bean actually causes them to meet thier maker. You in more southern climes would suddenly find castor bean in short supply.

  9. So it is only the seeds that are poisonous not other parts of the plant? I’ve read other parts of the plants are too. I’d like to know for sure.
    I use it in my garden, but have burned it rather than toss it over the fence for fear the horses or cattle would eat a leaf.
    Thx for letting me know.

  10. Sorry for the delay, karen! You’re correct, the entire plant is toxic, but the highest concentration is in the beans. You’re correct in keeping it away from the herbivores – though as I noted, I’ve seen it in fence rows and pastures. Maybe it tastes really bad?

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