Tuesday, April 21, 2009

Houseplant Toxicity Week: Part 4 (Potentially Dangerous Plants)

If you have landed on this page because you are concerned about a child or pet who has eaten a plant, seek emergency medical help.

In the U.S., you can call Poison Control at 1-800-222-1222 (for children), the ASPCA at 1-888-426-4435 (for pets; $60 consultation fee applies), or the Pet Poison Helpline at 1-800-213-6680 (pets; $35 fee applies)
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Part 4 of a seven-part-and-two-appendix series. (Part 1) (Part 2) (Part 3) (Part 5) (Part 6) (Part 7) (Appendix 1) (Appendix 2 - Index)

Part 4 is about plants which are only potentially or theoretically dangerous. Like Steven Segal. These are capable of causing harm and maybe even death, we think, but they are unlikely to do so in the amounts a person would be capable of consuming, or there's no real documentation to demonstrate that they've ever actually hurt anybody, or they can and do hurt people but it's not really all that serious, or etc.

Adromischus spp. As for Tylecodon spp., q.v.
Agapanthus orientalis (blue African lily) The sap is irritating to the skin or eye, and if eaten, the sap is alleged (by Toxicity) to cause open sores in the mouth. Considering this, I'd be surprised if it were pet-safe. Toxicity describes the sap as "not likely to be fatal, but can cause significant discomfort."

Aglaonema 'Emerald Bay'

Aglaonema spp. (Chinese evergreen) Allegedly edible if prepared in certain ways, but I don't recommend it and frankly don't see why anybody would want to try. Contains calcium oxalate crystals like other Araceae and would presumably also cause pain, swelling, etc. if chewed or if sap contacts the eye. Could probably be used for reptile / amphibian enclosures for strict carnivores which are not large enough to crush the plants.
Allamanda cathartica Sap contains a weak gastrointestinal irritant, which may cause cramping, diarrhea with dehydration, vomiting, etc. No reports about animal toxicity one way or the other, but I would expect this plant to be more dangerous to animals than to humans.

Aloe sp. This was tagged at Lowe's as Aloe harlana, but harlana is apparently rare enough that you wouldn't expect to find it at Lowe's, so it's probably something else.

Aloe spp. including A. vera (Alworthia 'Black Gem') Unlikely to kill humans or pets, but ingestion of large amounts is very uncomfortable. Main symptoms are diarrhea and cramping: when the bottle says "for external use only," they're not just yanking your chain. This is a general characteristic of species in the Aloe genus, though risk varies from species to species and some species are not safe even in small amounts. Diabetics may also experience hypoglycemia after ingestion of small amounts of A. vera. Safe for reptile / amphibian enclosures provided that the species being kept are strict carnivores, though it's worth paying attention to how many and how sharp the spines are: a species like Aloe variegata (partridge-breast aloe) or A striata would probably be fine, but vera or greatheadii, which have spines all up and down the leaf edges, might not be. Some people have bad skin reactions to Aloe vera gel, though this seems to be uncommon and is fairly easily dealt with. Most commercial products claiming to contain "Aloe vera gel" actually do, but in such tiny amounts that the toxicity due to Aloe compounds is very minimal: it's usually the other stuff in the product you should be worrying about. When A. vera causes people health problems, these are usually the result of applying the juice from the leaf directly to the skin, not ingestion.
Anthurium spp. (flamingo flower, oilcloth flower, tailflower) As with all Araceae, Anthurium spp. contain calcium oxalate crystals and likely cause pain, irritation, swelling, etc. if chewed. This does not normally appear to require medical attention but may be painful and may last for several days. Likely safe for carnivorous reptiles and amphibians.
Asparagus spp. (asparagus ferns) Everybody agrees that the berries are toxic to cats/dogs/children, though there's not any information about how toxic, and neither Toxicity nor Handbook bothers to cover these plants, so I doubt that you'd see anything beyond the usual nausea-vomiting-diarrhea. The plant in general is a mechanical hazard, because it has backward-curved thorns, which suck, and it may be more dangerous to cats than to other animals, because it's in the lily family, and plants in the lily family often seem to be specifically toxic to cats.
Aucuba japonica (Japanese laurel, spotted laurel) All parts of the plant are toxic, though most reports involve the (colorful) fruit. Symptoms of ingestion include the usual suspects: nausea, vomiting, cramping, etc. Complications don't look to be common, but dehydration (from vomiting?) may require medical attention, especially in children. Pet reactions are likely similar, but I didn't find any specific references to pets.

Caladium NOID. Photo by Carl E. Lewis, at flickr.com.

Caladium cvv. (angel wings, heart of Jesus, elephant's ear) As for Anthurium spp., q.v. Some sources seem to regard Caladium as a bigger threat than other aroids, but that could just be that there are a lot more Caladiums out there than some other aroids, 'cause they're so pretty: nobody provided any information that leads me to think that they're particularly more poisonous or anything.
Caryota mitis and other Caryota spp. (fishtail palm) Contains needle-shaped calcium oxalate crystals, which cause pain and burning sensations when chewed, especially on mucous membranes. Skin contact leads to itching, swelling and redness. Eye contact is obviously very much to be avoided. The fruits appear to be the most common source of injury, so occupational harvesting of the fruits and seeds is the main source of exposure. The base of leaf stalks may also contain more oxalate crystals than the plant in general. I found no information on pets but assume that the situation is more or less the same in animals as in humans: more painful than lethal.
Cestrum diurnum (day-blooming jessamine, day-blooming cestrum) Rare indoors. Leaves contain "calcinogenic glycosides," which I know what a glycoside is (a compound that contains some attached sugars as part of its structure), but "calcinogenic" puzzles me. The plant can apparently cause vitamin D intoxication, excessive blood calcium and low blood phosphate, bone softening, and will cause calcium to be deposited in soft tissues such as kidneys, with predictably bad results. The main concern is for grazing animals, which might eat large amounts, or small amounts over an extended period: there have been no documented human poisonings, and pets don't seem to be especially at risk either.

Clivia miniata in an outdoor planting, which makes me extremely jealous. Photo by "racka_roadrunner" at flickr.com.

Clivia miniata (kaffir1 lily) All parts of the plant contain the same toxin as in Narcissus and Hippeastrum, but at comparatively low concentrations. Most exposures result in no symptoms; in cases where there are symptoms, they are usually limited to vomiting and diarrhea. (No day at the park, obviously, but a big improvement on being dead.) Probably more of a risk to pets than to people, and maybe especially to cats, though I found no source that talked about it in any kind of detail w/r/t pets.
Cotelydon spp. As for Tylecodon spp., q.v.

Cyclamen persicum NOID.

Cyclamen persicum (cyclamen) The rhizomes are dangerous, for sure, though the taste is apparently spectacularly awful (Toxicity describes it as acrid and rancid), which makes it rare that anyone eats enough to cause a problem. The toxicity of the foliage is unclear but thought to be low. Considering how popular Cyclamen are, there are remarkably few actual cases of poisoning, and the symptoms Toxicity lists to watch out for (nausea/vomiting/diarrhea) are what they expect based on the compound thought to be the problem: apparently there have not been enough observations of actual poisonings to warn with any certainty. So be alert, but I don't think there's much of an actual danger here, however poisonous the plant might be.
Dracaena deremensis cvv. ('Janet Craig') ('Warneckei') I found shockingly little information on Dracaena spp. Neither Toxicity nor Handbook includes any Dracaenas, and the lists to be found on the internet disagree about whether or not they are toxic, though there seems to be some consensus that they are dangerous to cats and dogs but not people, reptiles or amphibians. (The reader is advised to be skeptical.) A few internet lists have Dracaena marginata down as toxic and the other Dracaena spp. as non-toxic, which makes me think that marginata might be a bigger risk, but it's really very difficult to tell. I'm fairly certain they can't be very toxic to humans, on the grounds that there are so many of them out there that if they were killing people, we'd be hearing a lot more about it.
Dracaena fragrans ('Massangeana') (corn plant) As for Dracaena deremensis cvv., q.v.
Dracaena surculosa (sometimes D. godseffiana; gold-dust dracaena) As for Dracaena deremensis cvv., q.v.

Dracaena marginata 'Colorama.'

Dracaena marginata (Madagascar dragon tree) As for Dracaena deremensis cvv., q.v.
Dracaena sanderiana (ribbon plant, lucky bamboo) As for Dracaena deremensis cvv., q.v.
Epipremnum aureum (pothos, devil's ivy) Accounts vary, but Epipremnum seems to be basically your standard aroid, and aroids all have calcium oxalate needles in them, which cause irritation, lots of pain, possible swelling, etc. If swallowed, expect vomiting and diarrhea. Possibly simultaneously.
Ficus elastica; not sure about cultivar. Photo from anonymous donor at Garden Web.

Ficus elastica (rubber plant) I originally had rubber plants under "Unpleasant," along with the other Ficus species, but subsequent research has made me think that rubber plants may be slightly more dangerous than the rest of the genus. Still unlikely to kill, I think, but if a child or pet ingests some, I would definitely seek medical/veterinary attention for it.
Grevillea robusta (silk oak) Grevillea robusta is one of those species that is more common in books than in commerce; I suspect at least part of the reason for this is because they contain chemicals very similar to the active agent in poison ivy (Toxicodendron radicans), which provokes a similar delayed but ferocious allergic reaction. This doesn't surprise me so much (I knew there had to be a reason why I didn't see it more often: I've never seen it in stores, and we've never been offered it from our suppliers.), but I'm a little perplexed as to why the books would fail to mention this. It's not like the rash isn't well-documented. In any case, it's not likely to do any more long-term damage than a similar case of poison ivy, and usually there seems to be no crisis that a prescription for corticosteroids can't fix. I have no clue what sort of risk Grevillea poses to pets. I imagine horrific outcomes if a child tries to eat one, but then, it's also possible that nothing might happen: like poison ivy, you apparently have to be exposed repeatedly before you'll react.

Homalomena 'Emerald Gem.'

Homalomena cvv. ('Emerald Gem') No lists or books mention Homalomena, but it seems reasonable to put it here because it's an aroid. So, as for Epipremnum aureum.
Hyacinthus orientalis (hyacinth) Similar to Clivia or Hippeastrum; nausea, vomiting, diarrhea, maybe drooling. It's rarely if ever fatal, because the toxins are concentrated in the bulbs, not in the blooms or leaves. The flowers' scent is also (unsurprisingly) known to trigger asthma for some people. The risk for pets is probably fairly low provided that unplanted bulbs are kept in a safe, inaccessible place.

Hypoestes phyllostachya, assorted cvv.

Hypoestes phyllostachya (pink polka-dot plant) I couldn't find any good information on how or why it is toxic, but there does seem to be general agreement that Hypoestes is toxic to animals, particularly cats but probably also to dogs. Human poisoning appears to be either unknown or exceedingly rare.
Mimosa pudica (sensitive plant) Causes hair loss in animals if ingested. The toxin, mimosine, when extracted from other mimosine-containing species and applied to human skin, causes hair loss. There don't appear to be any cases of hair loss from Mimosa pudica itself, though. A somewhat bigger risk, particularly to animals, is from the small thorns along the plant's stem, which have on occasion damaged the gastrointestinal tract of animals who ate them. Mimosine has also been shown to cause cataracts in rats, though that apparently took a while. So kind of a weird one all around. There were no cases of Mimosa poisoning known to Toxicity, though they do say that pets or children eating the plant over a long period might find all kinds of crazy shit happening. (My words, not theirs. Obviously.)
Monadenium ellenbeckii and probably other Monadenium spp. Caused one PATSP reader's dog irritation of mucous membranes and the gastrointestinal tract; happily, it was non-fatal, but still obviously unpleasant, and it's unclear what would have happened had a larger amount been ingested, or if it had been a cat / child / lizard / etc. instead of a dog.
Monstera deliciosa.

Monstera deliciosa (split-leaf philodendron, swiss cheese plant, ceriman) Most problems with Monstera arise from people trying to eat the (edible) fruit before it is fully ripe. Unripe fruit contains the calcium oxalate crystals all aroids have, and causes the same burning feeling, swelling, and pain. The ripe fruit is supposed to taste something like pineapple and banana (simultaneously), but causes hives for some people. If grown indoors, flowers and fruit are really unlikely, but the leaves also contain calcium oxalate and may be mildly dangerous as a result. I also have some reason to suspect that Monstera may, like Philodendron spp., be more dangerous to cats than most other aroids, though that's more a hunch than a fact.
Opuntia spp. (bunny ears cactus, prickly pear) The main danger from Opuntia is the glochids,2 which are very irritating to skin or eyes. This generally resolves itself sooner or later, regardless of what you do, but it's deeply and profoundly unpleasant. There may also be allergic reactions to glochids in some people, though it's not clear whether the reaction is to the glochids specifically or just the generic body reaction to a foreign object. The de-spined pads are eaten in some places, which is no big deal for most people but could in theory be dangerous for diabetics: ingestion of Opuntia has been demonstrated to lower blood sugar levels and blood insulin levels simultaneously, and could at the very least change the timing of an insulin-dependent diabetic's shots. Aside from the obvious danger to the eyes (and I suppose also tongue and nose), I'm not aware of any particular danger to pets.
Oxalis spp. (shamrock) Unlike so many other plants, Oxalis spp. contain soluble oxalate ions, instead of insoluble calcium oxalate. This makes Oxalis potentially dangerous, because free oxalate is highly attracted to calcium. So, you eat the oxalate, it finds calcium, binds to it, becomes insoluble, and then you have that much less calcium available for doing whatever it is your body does with calcium, which can be life-threatening if you eat a whole bunch at once. If you were to eat a smaller amount on a daily basis, it's not as big of a deal, though the calcium oxalate crystals you're continually forming in your system have a tendency to find themselves in the kidneys, where they can block important ducts and cause eventual kidney failure or whatever. The good news is that whether you're eating it all at once or in short portions over a long time, it does take a fair amount of the plant to cause these problems, so a kid tasting a leaf once, or a cat nibbling on a bit of the plant, will probably not lead to any serious problems.
Pandanus spp. (screw pine) One species, Pandanus amaryllifolius, is used in cooking as a flavoring agent, but the leaf itself is not normally chewed or swallowed. The leaves of some Pandanus species are known to contain calcium oxalate crystals, and are therefore probably irritating to the mouth if chewed, as with Schefflera. The spines on the leaf margins and midribs are also strong and sharp enough to be capable of wounding any child or pet who swallowed one, though they would also seem to be sharp enough to discourage anybody from making the attempt in the first place. The fruit of P. utilis is technically edible if cooked, but unpalatable.
Persea americana (avocado) Depends who you're talking about. Persea, even the fruit, is very dangerous to a lot of birds. It is also potentially lethal to cats and dogs, though I haven't come across many actual case studies, and it appears that the foliage is more dangerous than the fruit. Persea is relatively safe, on the other hand, for people: some people are allergic, and some people experience skin irritation after handling plants. Obviously one should still not rip off fistfuls of leaves and eat them, but it's not the most dangerous houseplant out there. Unless you're a bird.

Polyscias fruticosa var. elegans. Also called "parsley aralia," for what are hopefully obvious reasons.

Polyscias balfouriana (balfour aralia), P. crispata, P. fruticosa (ming aralia) These can cause skin irritation, with redness, inflammation, swelling, rashes, and other exciting features. In one case, a two-year-old who was seen chewing the leaves turned red and ran a fever, had a dry mouth and dilated pupils, had difficulty standing, and exhibited what are only called "peculiar" movements. Due to their relationship to Hedera spp., and the fact that they are known to contain similar compounds to the toxic components in Hedera, I'm inclined to say that they are probably similarly toxic. Wouldn't go crazy over it, but pets and children should probably be kept away.
Primula spp. (primrose, oxlip) These are uncommon as houseplants in Iowa, as far as I've experienced, though I hear there are a lot of them in parts of Europe. Most Primula spp. don't appear to be a problem, but P. obonica causes fairly severe skin allergies for a lot of people, and Primulas in general appear to have the capability to do so too, though only P. obonica does it often enough to worry about. The skin in affected individuals swells considerably, reddens, develops all kinds of gross-sounding discolorations and weird textures, and feels itchy or burny. Like with many plants, this is a bigger risk to people who work with plants occupationally, though florists, Toxicity says, are choosing to carry P. obonica less often than they used to because of the skin issues. (Perhaps this explains why I couldn't find a picture of P. obonica at davesgarden.com?)
Sansevieria cylindrica, other Sansevieria spp. As for Sansevieria trifasciata, q.v.

Sansevieria trifasciata 'Laurentii.'

Sansevieria trifasciata (snake plant, mother-in-law's tongue) Sansevieria trifasciata, and probably other Sansevieria spp., do contain a toxin, though it doesn't appear to be especially potent: in an animal test, it took 3 grams of Sansevieria per kilogram of body weight to kill rats. The toxin is not considered much of a threat to humans, but it is known to kill pets, specifically cats. Some people also develop skin irritation from contact with the sap.
Schefflera actinophylla (umbrella tree, octopus tree) Contains calcium oxalate crystals, like the Araceae (though it is in the Araliaceae instead), and causes similar irritation, swelling, pain, etc. There is also an allergen which can cause rashes and blistering, particularly in those exposed occupationally (like greenhouse workers, florists, propagators).
Schefflera arboricola (umbrella tree, octopus tree, arboricola) As for Schefflera actinophylla, q.v.
Scindapsus pictus (satin pothos) As for Epipremnum aureum, q.v.
Senecio cineraria (dusty miller) Though not often kept indoors, Senecio cineraria is a common enough container plant, and may pose some threat to children and pets. All Senecio spp. are theoretically dangerous, though actual cases of poisoning generally require continued ingestion over a long period of time (like weeks or months). Usually the liver is the affected organ. It seems unlikely to me that children or pets would be much at risk from Senecio: it appears to take a lot of plant material to cause the toxic effects, more than one could normally eat at a time, and continued consumption over months would be pretty obvious eventually, you'd think. Grazing animals are at more risk, but even then it seems like kind of a long shot.

Senecio macroglossus.

Senecio macroglossus (cape ivy) As for Senecio cineraria, q.v.
Senecio mikanioides (German ivy) As for Senecio cineraria, q.v.
Senecio radicans (string of bananas) (by association) As for Senecio cineraria, q.v.
Senecio rowleyanus (string of beads) (by association) As for Senecio cineraria, q.v.
Senecio x hybridus (cineraria) (not often kept as a houseplant) As for Senecio cineraria, q.v.

Spathiphyllum sp.

Spathiphyllum spp. (peace lily) As for Epipremnum aureum, q.v.
Strelitzia reginae / nicolai (bird of paradise) Neither Toxicity nor Handbook mention Strelitzia spp., but it is usually on the toxicity lists. In a couple places, the warnings are specifically for the flowers and seeds; it's unclear whether the foliage is toxic as well.
Syngonium podophyllum (arrowhead vine) As for Epipremnum aureum, q.v.

Tagetes patula, various cvv.

Tagetes spp. (French marigold, African marigold) More of an outdoor container plant than a houseplant, but often enough found around the home to be worth including here. Skin irritation is the usual issue, and Toxicity uses words like "oozing" and "scaling" and "burning pain" to describe this, so if you react to these, well, um . . . sucks to be you. The odor of the flowers - not the pollen, but the odor - causes asthma in some people too. Ingestion is not known in people, though weirdly enough, people experiencing the skin irritation sometimes also report diarrhea at the same time. Cattle which eat Tagetes get bloody diarrhea. That said, I think these are probably of fairly low risk to pets, who probably know better than to go near something that smells like that, and although children probably have ingested them before, Toxicity couldn't find any cases describing it.3
Tulipa spp. (tulip) Nobody has much of anything to say about eating tulip leaves or flowers, which doesn't necessarily mean they're safe, but does suggest that maybe they're not a huge deal. Tulip bulbs, on the other hand, can be seriously inconvenient. There are two main types of tulip-related issues. The first, from ingestion, is pretty straightforward, and results in drooling, nausea, vomiting, and occasionally difficulty breathing or heart palpitations, though that's apparently as far as it goes: it doesn't appear that anybody usually dies. Though I imagine you could if you had a burning desire to commit suicide-by-tulip. The second type of problem with tulip bulbs is mostly occupational, and results in a rash and inflammation of the hands, brittle nails (the nails thing happens to almost everybody who handles tulip bulbs occupationally), skin peeling off, etc. The rash can sometimes spread to other parts of the body, though that's not common. For some people, breathing the dust from tulip bulbs, or getting it in their eyes, can also cause brief allergic reactions. Most of this appears to be preventable by wearing nitrile gloves when handling tulips, and hobbyists in most cases wouldn't handle enough bulbs to have this happen, though if your fingertips tingle and your nails go brittle following a lot of tulip-planting, you might think about switching to daffodils next year. Or maybe wearing gloves.
Tylecodon spp. One site reports that Tylecodon spp. has been implicated in killing livestock often enough that farmers and ranchers in its native South Africa pay people to comb through their fields and pull them all up. Toxicity confirmed that Tylecodon is poisonous, in a manner similar to Kalanchoe spp. (on the Unpleasant list), though it didn't really go into any detail. The Amateur's Digest appeared to be suggesting that some species of Tylecodon are much safer than others, but A) that's not necessarily true, and B) even if it were, there's no comprehensive list of which are which, and C) most of us are not Tylecodon taxonomists anyway so who cares. Most of the above also applies to the genera Adromischus, Cotelydon, Kalanchoe, Sedum and Senecio: as a general rule, any smallish succulent where you're not really certain about the ID should be treated as potentially dangerous to pets and children. Kalanchoe, Sedum and Senecio are all given their own listings elsewhere in these plant toxicity posts.

Zamioculcas zamiifolia.

Zamioculcas zamiifolia (ZZ plant, fat boy, eternity plant) As for Epipremnum aureum, q.v.

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Photo credits: Mine, except for Caladium and Clivia. Credits for those two are given above.

1 Apparently kaffir is an ethnic slur in South Africa, though "kaffir lily" is still being used in a lot of the houseplant literature and on houseplant websites. I include the name in order to facilitate web searches for the plant, but mean no disrespect to black South Africans by doing so. At work we just call them "clivias," a practice I suggest the reader adopt.
2 Glochids are barbed bristle-like spines found on some cactus species, particularly Opuntia spp., and are the work of the devil. They are very easily detached from the plant, and have on occasion been blown off of the plant into people's eyes, or on their skin. They're incredibly irritating in both literal and figurative senses, and I was very memorably traumatized by one at my grandmother's house when I was a child. Toxicity of Houseplants recommends removing large, visible spines (if any) with tweezers, and then removing glochids by covering the affected area with household water-soluble glue (like Elmers) or depilatory waxes and then removing the glue/wax, which will get rid of about 95% of the bastards. Adhesive tape is sometimes also used but is only 30% effective. (I've tried tape at work: I think 30% might be optimistic.)
3 Puzzled because you'd always heard that marigolds were edible? I sympathize. The explanation appears to be that marigolds of the genus Calendula, also known as "pot marigold," are edible, but Tagetes ("French marigold") are not. Some hopeful people think that the toxins, whatever they are, might be confined to the leaves and stems of Tagetes, making the flowers still edible. I won't say they're wrong, but I don't recommend taking that chance, because as far as I know the scientific evidence for this theory is exactly zero. Both the French marigold (T. patula) and the African marigold (T. erecta) should be avoided, though if you've mistakenly included a couple flowers in a salad, thinking that they're Calendula, um, call your doctor about it, but I expect you'll probably be fine so long as you don't do it again.


12 comments:

John de said...

Hello,
You have done such a great job with this, congratulations! I will be refering to it often.
I just wanted to add that my partner and I drink Aloe vera juice quite frequently and we love it. You can find it in any Asian food store. It has to be processed (I think they actually remove the /sap/ (or gel) from the /juice/). So it is true that in its natural form if you chewed on a leaf it would not be good, but properly processed it is a delicious beverage. Just an interesting side note.

Karen715 said...

Thanks for a wonderful series thus far.

I actually have a personal experience to relate regarding Epipremnum aureum. When I was maybe seven or so, I decided, for whatever reason kids decide such things, to chew on a couple of pothos leaves. I don't remember if I swallowed them, but I probably did. I experienced a mildly painful tingling/numbing sensation in my mouth. It wasn't bad enough for me to mention it to anyone, and I suffered no digestive effects. (This is why I am uncertain that I swallowed--but I don't remember spitting them out either.)

In fact, it wasn't bad enough for me not to try it again, a few weeks later. (In retrospect, I think I didn't actually associate the unpleasant sensations with chewing on the leaves. It's hard to believe that I was generally considered to be a smart kid.) After experiencing the tingling/numbing a second time, I did recognize that there was a cause/effect going on, and never did it again.

mr_subjunctive said...

John de:

Oh. Duh. I remember seeing products like that around here, though I've never tried them. I should try to find out how that's processed to be edible.

Karen715:

So, not the "immediate intense oral pain" that Handbook claimed, then?

I suspect that thepoisongarden nailed it in the comments to part 1, that most poisonous stuff is unpleasant to taste, so people and animals usually spit it out before getting a harmful dose. And then there's also that whole thing of most exposures not resulting in symptoms even when one does get a potentially harmful dose.

I'm still afraid of my Euphorbia tirucalli, though. More so now that I've had two people in two weeks tell me about occasions when they've gotten sap in their eyes: one customer at work last week, and then one PATSP reader this week. Both agreed that it was the worst pain ever. Made me glad I wear glasses: not full eye protection, but so much better than nothing.

Homegrown Evolution said...

Mr. Subjunctive,

This is a fantastic blog! We grow Opuntia in our front yard for the edible pads and fruit. I burn off the glochids over an open flame on the stove. But inevitably some glochids end up on the kitchen counter leading to some intense marital arguments during Opuntia harvesting season. The pads are very tasty with scrambled eggs (called nopalitos in Spanish) and the fruit makes a tasty jelly.

Keep up the good work--it's so nice to see footnotes on a blog!

mr_subjunctive said...

Okay. A little googling around has revealed that, one, the toxin in Aloe barbadensis is mainly concentrated just under the skin of the leaf. So part of processing is apparently just about trying to get at the stuff in the middle without contaminating it with too much of the outside.

A lot of places that prepare aloe vera juice for consumption also treat it with activated charcoal, which I'm assuming is there to absorb the poison. It's apparently possible to prepare it yourself, if you're careful about how you do it, though self-prepared aloe juice is not recommended for internal use, even by the people who will tell you how to prepare it. (Link.)

John de said...

Thanks for looking into the Aloe juice-- you're great. I've also used the gel of a freshly broken leaf of A. barbadensis to sooth burns, cuts, insect bites, and scrapes-- works like a miracle. I guess that's why it's also called medicine plant.

Peter said...

I have a customer who buys Sansevieria cylindrica because her mother eats it for good luck. No, really.

Also, we consider Tylecodon to be the most dangerous plant we carry, but I suppose we could be overreacting.

mr_subjunctive said...

I have a customer who buys Sansevieria cylindrica because her mother eats it for good luck. No, really.Well, clearly it works: I'd say she's lucky she's not dead.

Actually, though, I didn't run across too much about Sansevieria that made it sound terribly dangerous to people. Animals, yes, but not people. So I suppose she's not really that lucky.

Tylecodon the most dangerous plant? Seriously? More than Adenium and Euphorbia? I'm whomperjawed.

lancetx said...

I have to agree Tagetes are unpleasant for me to be around, more due to allergies than anything else though. So it's either the pollen or odor that gets me.

I must agree about Glochids too, I spend a lot of time in areas with prickly pear, and those tiny invisible thorns are the worst. I have had a few that the red spot(s) from them has lasted for a couple of years.

Paul said...

Interesting that marigolds were on the list. I wonder if it is only the leaves that are an issue. I have read of the flower petals being used in salads to add color and a light peppery taste.

Anonymous said...

Do you know if a Hypoestes plant is toxic to chameleons? I know they are from the same region but I can't find any info any where.

mr_subjunctive said...

Anonymous:

As I think I mentioned somewhere in the preamble, very, very few sources bother to say anything one way or another about reptile toxicity, so I really couldn't guess. That said, aren't chameleons carnivores, who wouldn't be eating the plants anyway?