Welcome to my toxic, painful gardenBy Geoff Stein (palmbob)
March 8, 2008
This originally began as an article about toxic plants and pets, but it was hard to ignore the other potential dangers of these plants, so it evolved into a dangerous plant article. Well, THAT would be one huge topic so I decided to limit it to plants in my very own yard, as I do have an abnormally large number of toxic and spiny things, particularly for having such a dinky yard. I hope my experiences as a veterinarian and a grower of sharp things can give the reader a fresh perspective about the hazards, and perceived hazards, of growing/ having certain plants.
There are many long lists of toxic plants on the internet and in magazines and books. But very little detail is available for consumers in terms of severity or potency of these toxins, nor how likely these toxic plants will get into you or your pets. As a veterinarian working in emergency medicine I see many cases of poisoning in animals, but actually very few plant poisonings or injuries. When one peruses over the toxic lists of plants in my yard, and learns of all the spiny dangers lurking there, one might conclude that in order for pets, children or neighbors to be allowed even to venture out the back door they should have their mouths taped shut, heavy goggles applied and be wearing a coat of armor…. The other option would be to have the place bulldozed first and turned into a cement desert or featureless lawn in the name of safety. You would think my knowledge of veterinary medicine would have kept me from stupidly growing such a dangerous garden, especially with 8 dogs, 2 cats and a bird that spend a lot of time out there. In my own defense, I have planted most plants up in raised beds that have been ‘fenced’ off from the pets, but of course this does not stop the cats or bird, and some of the dogs still figure out ways to enter this hazard zone. And I rarely have company over, but I still would not feel the need to have them sign waivers in order to spend time in the yard. In reality, it is the plants really who need protection from intruding pets and people. But that is a topic for another article, perhaps. The following is a brief discussion of the toxic and dangerous plants I grow in my own yard and how realistically serious a health hazard they actually may be to pets and people. Each plant will have a rating of 1-10 with 1 being a mild to non-issue in terms of my concern, and a 10 is one I am most concerned about.
Aloes are included as toxic plants on many lists, though cases of actual poisoning are basically unheard of. Aloe vera, the most commonly grown plant, is in many pet ‘natural’ medications, both topical and oral, and no reports of toxicity exist. Aloes do contain saponins which can cause mild to severe gastrointestinal signs (vomiting, diarrhea and abdominal pain) as well as tremors. A few species are known to be quite toxic (but these all turn out to be very rare species, with few, ifa any in collections.. yet). My own bird ate most of an Aloe vera plant and no symptoms of any kind were noted afterwards. But as it is a potential toxin, a general recommendation would be to try to at least be cautious with oral products containing aloe vera. I rate Aloes a 1 for toxicity and a 3-6 for physical danger (some have very sharp, hooked spines).
Aloe ferox seedlings and Aloe vera (latter not from my garden) are both common sources of skin and oral medications- not very dangerous
Agaves- some sites rate this is a toxic plant, but realistically it is not very toxic, either, and actual cases of toxicity are so rare, I could not find any. However, many of these do have very stout sharp terminal leaf spines, and many have even sharper marginal leaf thorns. I rate this a 1 on the toxicity level, but nearly a 10 on the danger level (mostly in fear of poking a visitor’s eye out, particularly a child’s, or ripping someones arms to shreds that gets too close). These are probably the most dangerous plants I have in the garden in terms of human hazard potential. Pet danger potential is much lower (thanks to pet’s having fur coats and being more coordinated than us humans).
one unknown species in my yard- this is a truly viscious plant- dangerous!
Dioscoreas- these are wild yams and uncooked can be pretty toxic (have saponins in the wood caudex). If eaten, the toxins can cause a very uncomfortable rash in those that eat raw tubers. However the poisons are easily removed by boiling. Dogs rarely cook their own food, but the toxins are not highly dangerous, so I give this plant a 3 on the toxicity scale and a 0 for physical danger. Mine are in pots up off the ground so no risk to dogs unless a squirrel were to knock one down.
my toxic Dioscorea collection
Yucca is also on some toxic plant pet lists, but I am unclear why. I certainly have never heard of a case of yucca poisoning, and from what I can tell it is only mildly toxic. My yuccas are all fairly ‘soft’ leaved, too, except for Yucca rigida, so most are not serious sources of potential pain or injury… but even the softer leaved plants have very sharp leaf-tips and most of these yuccas have lots of leaves making the spines harder to avoid than, let’s say, and agave of similar size. So I rate these a 1 on the toxic scale and an 8 on the ocular danger level.
Yucca rigida in pot- not that toxic, but ouch!
Kalanchoes are succulent flowering plants in the family Crassulaceae and are on the ASPCAs top ten most common toxic plant list. These plants do have significant toxicity that is far and above just about anything else in that family (most Crassulaceas are considered non-toxic). Probably the most commonly grown Kalanchoe is Kalanchoe bossfeldiana, sometimes called the Florist’s Kalanchoe, a common and beautiful house plant (or landscape plant in frost-free climates). These plants have poisons that can cause damage to the heart and should be considered a real potential danger to your pet (dogs, usually- cats rarely try these). However, actual cases of toxicity are relatively rare as these plants taste pretty bad and few dogs will eat enough plant tissue to make themselves sick. Still, some toxicities and deaths have been recorded. This is a plant you really do want to keep away from your plant-eating dogs or plant-tasting cats, just in case. I rate Kalanchoes about a 9 out of 10 on the toxic plant scale, but a 0 otherwise.
Kalanchoe bossfeldiana (not mine- they never look this good)- left, and Kalanchoe luciae (right) in pot out of harm's way (I hope)- these are pretty toxic plants, but not too many dogs will eat them
Pachypodiums (aka Madagascar Palms) are fairly common house plants in most of the USA, and wonderful outdoor landscape species in the nearly frost-free zones such as mine. This plant has toxins that have been historically used for poison tipped arrows, so the toxins are fairly serious (related to Oleander). However, most species commonly grown are heavily armed with spines and taste horrible (reportedly), and actual toxicities in small animals are nearly unheard of. I have many pachypodiums and none of my pets have shown any interest in these noxiously spiny plants. I rate these a 5 in terms of potential toxicity to my own pets, but an 8 in terms of physical danger (poking into an eye, etc.)
Pachypodium geayi clump up in safety of planter bed
Plumeria are in the same family as Pachypodiums, Adeniums and Oleander as well, but again actual toxicity cases are rare. These have more of an irritant toxin than a serious threat to life (unless a significant amount could be ingested). My dogs have chewed on plumeria cuttings without apparent ill effects, but most quickly give up the task, presumably thanks to the irritant qualities of the saps. When trimming these plants one must be careful not to let the sap drip down into the eyes- cases of blindness from this have been reported. I rate these a 3 in terms of pet danger and a 4 for physical risk (sap irritation).
Plumeria in the yard (again out of the way, but leaves fall off)- not too dangerous
Cycads are 'pseudo-succulents' that are rapidly increasing in popularity as collector plants. The Sago Palm (not a real palm) is the most well known and planted of the cycads. Toxicity cases in dogs with this species is actually fairly common and can be very severe, even fatal. All parts of these plants are toxic, though most are spiny and are highly unpalatable. But the seeds can be attractive to dogs and are the most toxic part of the plant. Liver failure is the main concern with ingestion of this group of plants, but the poisons in cycads can also cause bleeding problems, severe GI upset, coma etc. I own many cycads and have a lot of pets, too, and have yet to see a case of poisoning, but I am careful to remove all seeds/fruit of these plants from the area the dogs or bird can get to. My own dogs have occasionally managed to chew up a cycad seedling, though usually only gnawing on the roots (still quite toxic), but obviously not enough to do themselves any harm. But that has been a concern of mine from day 1. If you own a dog that likes to dig up plants and gnaw on them, maybe these would be plants best left in tall pots or kept out of your yard. I rate cycads, as plants, an 8, but the fruits as a 10, on the toxic scale. From a physical hazard point of view, I rate these a 2-7 (depending on the species), for the human injury potential. Animals seem oblivious to their spines. My pets seem to not notice how sharp the leaves actually are until they bump into them and I am sometimes concerned about their eyes… but so far, no problems.
Sago palm and Dioon (left photo-away from pets) and Encephalartos horridus in right photo (no dog in his/her right mind would try to chew on this anyway)- pretty dangerous plants for several reasons... but the fruits are the really toxic and attractive items. None of my cycads are old enough to make fruits, yet, thankfully.
Cacti- Fortunately I have few if any toxic cacti… but most of my cacti (over 300 species) are covered in spines that would prevent my pets from even trying to chew on them anyway. My concerns about cacti are the long spines that could blind one of my pets or perhaps a visiting child. Thankfully this has not happened, yet, but I do see at last one case of cactus spine in the eye of a pet a year at the emergency clinic, so am a bit concerned about this sort of injury. Thankfully most of my dogs seem to be able to avoid these plants, though the cats seem less concerned (but very coordinated and probably unlikely to injure themselves). The main problem I have had with cacti are the dogs stepping on shed spines or having cacti glom onto them as they sneak through the garden beds. I have one Ferocactus seedling that has been relocated by one of the dogs over and over again (grabs onto his fur and goes for a ride). And then we get injured when we pick up the dogs all covered with spines. The bird avoids cacti as a rule (birds have excellent vision and can probably see spines other animals might not notice). Some cacti have very small spines called glochids and these spines are incredibly annoying and irritating (to me). I rate cacti a 1 in terms of toxicity or ingestion problems, but a 9 in terms of eye danger and overall general annoying pain.
These are some of the more dangerous plants (to my own person, at least) in the garden- very painful and annoying
Euphorbias- the most infamous of all the holiday plants is the Poinsettia of course, and yet it has been shown over and over to be only mildly toxic to pets, potentially but rarely causing some GI upset or skin irritation from the saps. However, there are many other more toxic and irritating Euphorbias in my yard, with the pencil cactus (Euphorbia tirucali) being near the top of the list. This plant is the most sensitive to being bumped and easily ‘annoyed’, and responds with oozing a lot of thick, white, toxic latex from its every injured pore. Though I luckily seem to have minimal sensitivity to Euphorbia sap, many are highly sensitive to Euphorbia saps and develop severe rashes wehn coming into contact with this sap. I have gotten this stuff in my eye and that was indeed a most unpleasant experience. So far the Euphorbias have been a non-issue with the pets in terms of toxicity as they avoid them completely. Even the bird, who likes to take a nibble out of everything, seems put off by Euphorbias. I rate Euphorbias a 2 on the toxicity level, but a 6-8 on the potentially painful rating (some also have very sharp thorns).
Poinsettia (left) growing outdoors (not too dangerous) Euphobia echinus (right) in planter box (moderately painful) Sticks of Fire to be planted (moderately irritating) in photo underneath
Succulent Bulbs: I have a few above-ground-growing succulent bulbs that are known toxic plants, though, again, I have can almost no cases of actual poisonings by any of these species. However, I grow them mostly in pots out the pet's way, and so far no problems. Local squirrels frequent these pots, digging holes in them and hiding seeds... but seem to leave the bulbs themselves alone. There is nothing physically dangerous about these so I rate these a 4 on the potential toxicity scale and a 0 on the physical danger scale.
Bowiea volubilis (left) aka the Climbing Onion is one of my favorite plants and reportedly fairly toxic; right is one of many of my Albuca bracteatas (aka Ornithogalum longibracteata or Pregnant Onion). This plant is basically a weed in my garden, but still a curious and interesting plant and reported a toxic one, too.
Non succulent bulbs: I am not a big flowering plant grower, but I have grown my share of garlic, agapanthus, lilies, daffodils, freesias, tulips and amaryllis. All except perhaps the freesias should be considered serious potential toxins for pets, and particularly the lilies for cats. Why lilies are so toxic to cats is still unknown, but if even a tiny amount is ingested, it can lead to kidney failure. Lilies are commonly kept as house plants and very popular around Easter. Cats like to nibble on green things, and often taste lilies before deciding they do not taste good… but sadly, all it takes is a taste sometimes to cause serious ill effects. This, to me, is a 10 on the potential toxin list, at least as a house plant. In yards where there are so many other green things to nibble on, the potential dangers to cats are far less (but still there). I no longer grow lilies except a few day lilies (though admittedly not for reasons of toxicity- I just have no room for them).
Easter Lilies indoors and Tiger Lilies outdoors (photos by nativeplantfan and echoes)
All the bulbs are toxic to dogs (and to cats, but I have never heard of a cat eating a bulb) and some dogs will dig these plants up and eat them. Thankfully, this is not a common occurrence, but I have seen at least 2 toxicities from toxic garden bulb ingestion (neither were seriously ill, though) in other people’s pets. I rate all these garden bulbs a 7 out of 10, but since they are not in the dog right area, I am not actually concerned.
Daffodil in my yard (no takers in terms of munching to far)
The only bulb requiring further discussion is garlic. Onions and garlic are toxic bulbs though few dogs would purposely eat such plants. However, low-grade toxicities from garlic are very common- perhaps the most common plant toxicity in pets that there is (though few are serious and most go undiagnosed). Why? Because we humans purposefully feed it to them, thinking it’s actually good for them. It is NOT. Garlic, even in small doses, is toxic, in any form. Thankfully most dogs do not get enough to do them permanent or serious damage, but many more get true toxic doses than anyone realizes. Garlic is a common ‘natural’ cure for all that ails both people and pets. However, there is no reason to give any garlic to dogs or cats. It is NOT a good product for flea or any parasite repellent, nor is it good for anything else that ails a pet. And it can cause gastrointestinal damage, bleeding, liver damage, and most commonly a serious and potentially fatal form of anemia if eaten in large quantities. I rate my garlic bulbs as a 2 only because my pets will never eat them or be interested in them, and it takes a LOT to really show a serious toxicity... but do not ignore this toxin!
Society garlic (photo by Xenomorph); supplement found in pet store with garlic in it- just because it's for sale doesn't mean its safe
I realize this is potentially a huge category, but I have very few flowering plants, so for me, it is a small one. The only flowering plants I have grown of note are Oleander (super-toxic!), Bird of Paradise (both the Strelitzias and Caesalpinias), Azaleas, Lantana, Morning Glory , Brugmansia and Nandina (that last one is a weed planted by the previous home owner and I can’t get rid of it). Oleander (I no longer grow this) is a very toxic plant- one of the most toxic there are. Still, I have never personally heard of a case of pet poisoning with this plant (livestock poisonings are common, as cattle will eat anything they come across). It has a horrible taste. But it is a deadly cardiac toxin and only a small amount eaten can be deadly. I often marvel that there is more than enough oleander grown as a highway landscaping plant in California to kill every human on the planet. The more common problem with this species is as an irritant. Those that prune this plant often complain of serious rashes from its saps (sometimes worse than Euphorbia rashes). I rate Oleander a 10 on the toxic scale and a 7 on the physical danger scale.
Oleander (photo by Clare_CA)
Azaleas have a similar oral toxicity (actually a different toxin, but end result the same), but the contact irritant potential is far less. These are also a 10 toxic scale-wise, but a 1 otherwise.
Azalea similar to the one I grew once (photo by Bigcityal)
Lantana is a fairly toxic plant but it is mostly a herd animal hazard. The berries and leaves have some serious toxins that can cause GI signs and liver failure, but rarely are dogs or cats affected (few dogs or cats can stomach the horrible taste). Some reports of children eating berries have resulted in notable toxicities, but the outcomes were not discussed. Birds seem to be pretty resistant to the toxins as I see them eating the berries all the time (not my pet parrot, though). This plant is about a 6 in the toxic rating scale, and a 3 on the irritating scale (has nasty fuzzy spines that are hard to remove from ones skin).
Lantana in my yard- up and out of the way- mildly dangerous
Strelitzias are supposedly toxic, but actual toxic episodes are very rare. My dogs routinely tear up the leaves of this plant (doubt much is ingested) with no ill effects. These are a 1 on my toxic scale.
Dogs chew this up all the time- minimal danger
Caesalpinias have a neurotoxin but severe cases of poisoning are rare (though rabbit deaths have been recorded). None of my pets are interested in these. Caesalpinias rate a 5 on my toxic scale and a 2 on the physical scale from having a few spines.
also referred to as bird of paradise, this one is a tad more toxic, but still not a huge concern
Morning Glories have an LSD-like toxin and ingestion, particularly of the seeds, can lead to hallucinations (don’t know if my dogs have ever hallucinated) but actual cases of poisoning, at least in pets is rare. I no longer have one of these as I consider it a ‘super weed’ (nearly impossible to eradicate). These rate a 2 on my toxic scale and a 2 on the physical scale (has some urticating hairs that are annoying when digging up).
one of the worst things I could have planted in the yard- but not from a danger standpoint
Brugmansias are another infamously toxic plant in the nightshade family, and surprisingly there are many cases of human poisonings from this plant (all intentional and most ‘recreational’). This is a hallucinogenic plant but its actual toxicity is probably quite exaggerated. There are no reports of pet toxicities that I could find, and all the human toxicity cases in people I read about resulted in a lot of loopy, stoned people, none of which died, even after ingesting concentrated forms of this plant. I rate this a 4 on my own toxicity scale, as mine are making seeds and I assume the seeds are likely more toxic than the rest of the plant. Thankfully these are also in the front yard and the dogs live in the back- so they will never even get a chance to eat the seeds.
living death? I think not. But don't eat it just in case.
Nandina, or Heavenly Bamboo, is a very toxic plant and thankfully mine is in the front yard far from the dogs. Again, actual cases of toxicity are uncommon, but it has some cyanide in the berries. Oddly birds seem to be resistant to these toxins. This is more of a concern for livestock than for most pets. These rate an 8 on the toxic scale, a 1 on the physical problem scale, but a 10 on my nuisance scale (since I can't seem to get rid of it).
Mine has yet to grow berries like this one (photo pdb_eloopj)
These are not really non-flowering, but the flowers are not the attraction at least. Most of these I consider foliage plants: Philodendrons, Monsteras, Alocasias, Ivy, Draecenas, Caladiums etc. Almost all these plants are toxic thanks to oxylates in the foliage. Ingesting oxylates cause a lot of irritation all along the GI tract (as far as they get before being vomited up). I have to say I have seen a fatal toxicity from a manic dog gobbling up an entire Diffenbachia, but that was a pretty rare occurrence. My dogs do not mess with any of these plants- guess a chew or two and that’s that. The bird has nibbled on a few philodendrons, but without apparent ill effects. Cats usually avoid these plants. I rate these about a 3 on the toxic scale.
Philodendrons and Alocasias in my yard- dogs don't go in this part of the yard, but toxicity concerns are extremely low anyway
Ivy has a different toxic principle, but actual poisonings from eating ivy are also rare, presumably from it tasting bad. However, ivy can be a real problem for herbivorous pets, like rabbits. Again, most do not eat enough to cause a problem. I rate ivy a 3 on the toxic scale (since I don’t own a rabbit) but a 3 also on the phsyical scale (as it is easy to trip in this stuff and fall down).
Ivy above ground, but trails to dog level- no interest. Minimal danger concerns
Really the only plant I put in this nebulous category is the grape. I have 6 grape vines and grapes fall to the ground now and then, and my dogs have all had several. Well, as it turns out grapes are very serious potential toxins. What is odd is that most dogs that eat them are not poisoned for some reason. But some are and severe and potentially fatal kidney damage can result. For this reason I am pretty industrious about collecting the grapes before the dogs do. I have noticed the parrot eating an enormous amount of grapes, but apparently they are not toxic to birds. I have not seen/treated a case of grape toxicity, but numerous cases show up on the ASPCA case log weekly. I rate grapes as an 8 on the potential toxic scale, just in case any of my dogs are susceptible.
These grapes were all ingested by my dogs and this WAS a big concern of mine- thankfully no sensitive dogs ate them. From now on I will be more careful to harvest grapes sooner. Though these seem inocuous to most people and I think are only moderately toxic, I would probably rate these grapes as an 7 out of 10 on the likely toxicity scale in my yard (to pets only, not people of course) as they are probably the most likely, of all my toxic plants, to actually be eaten by my dogs. Birds thankfully do not share the canine sensitivity to grapes and raisins. And cats simply don't like them.
There are few very toxic trees one can grow, but I don’t grow too many myself. Scheffleras are on the endless plant toxic list for the same reason as most of the above foliage plants- oxylates. My tree is out front away from pets (not for the reason of toxicity, though). I have never seen/heard of a case of toxicity with this tree. Rating is a 1.
one of two Scheffleras, both in front, but would be very little concern anyway if these were in back with pets
I do grow a coral tree which has moderately toxic bark and roots, but the seeds are very toxic (mine is out front, again, and also years from the seed-making stage). There are several potent toxins including alkaloids that can potentially cause vomiting, diarrhea and even respiratory paralysis, as well as cyanide. This might be a tree I would not want to grow and get large in a yard where many curious dogs were confined. Still, actual cases of poisoning are rare (I have never seen one). Actual pet poisoning cases are very rare. Still, I would rate an adult tree an 8 on the toxic scale, and a 6 on the dangerous one (many Erythrinas are heavily armed with thorns as is mine).
my own coral 'tree'... some day. Seeds are VERY toxic. Planted in front away from dogs
Flowers of my coral tree... mildly toxic, but nothing compared to the seeds that follow
Citrus trees are non-toxic, but some have horrifically sharp, thick, strong spines (like my Lime tree). Why I planted it near an area I go by all the time is beyond me. Fortunately the spines are far above the animals, so they are not in any danger, but I rate this a 7 just for human danger.
not toxic but very hazardous tree
Manihot- this is a relative of the tapioca tree with toxic leaves and bark (contains a cyanide poison). The leaves are quite toxic, but thankfully also extremely bitter, so few animals would be able to ingest enough to do themselves some harm. I have never seen a poisoning from Manihot, but then it is a fairly rarely grown plant. I rate this a 5 on the toxic scale, but actually danger is far less.
moderately toxic but unpalatable (Manihot grahamii)
Bunya Bunya tree- this Araucaria is like a giant, spiny cycad of a tree- non-toxic but very sharp and spiny. I think I am stabbed by this tree’s lower branches more often than by all the other plants in the yard combined (and that’s a LOT). But in terms of actual danger, it is probably only a 3. Mature bunya bunya trees develop very heavy cones that can easily crush a person’s skull should one be unfortunate to be hit by one… but my tree is many decades from that stage of growth, and that is still a very unlikely event, regardless.
nontoxic but incredibly spiny tree
And of course, I have lots of palms, all which are non-toxic and ‘user-friendly’ except for the Fishtail palms and Arenga (Sugar Palm). These two genera of palms produce toxic fruits (oxylates again) that not only can cause very severe oral inflammation (not to mention the rest of the GI tract) if ingested, but are actually irritating just to handle (will burn the skin if the juices get on one’s hands). Thankfully, mine are all seedlings and a good decade away from making seeds… and are in the front so the dogs will never be tempted to eat one. I rate these a 3, only because fruits are more easily gobbled up than other parts of plants, but I have not heard of a single case of pet poisoning from these palms.
my own Caryota seedlings (left) maturing seed from Caryota mitis (photo by bigcityal- right)
Arenga engleri (my palm is younger and not made seeds like this yet)
So as you can see that despite the large number of toxic plants in my yard, probably my major concerns are over personal injury, not pet or human toxicity potential. The paranoia associated with plant and pet/child toxicity needs to be modified with a touch of reality. But proper respect of all sorts of plant dangers is still wise. Just keep things in perspective, as I and my pets do.