Thursday, December 25, 2008


Both Dermal and Oral toxicity levels should be considered if potential for injury to the purchaser exists. I suggest a special rating should exist for those plants that have bright berries or seed pods that look edible. The laburnum, castor bean and skimmia come quickly to mind. In the case of the laburnum, by simply growing the less fruitful cultivar x waterei ‘Vossi’ near eliminates the risk. It rarely sets seeds.
Some of the risks are simply mitigated by properly deadheading spent flowers before they create seed. Lupinus as an example. For dermal toxicity wearing gloves will protect your hands – something this gardener rarely does.

Allergic skin reactions.
What is news to some people is that dermal reactions may sometimes take 24- 48 hours to appear. It is easy to remember and to avoid the nettle or poison ivy/sumac that appears suddenly, it is less easy to deal with allergic reactions that occur days later.
Some reactions also occur only if one comes into contact with the plant in sunlight—or are chemicals that make the skin very sensitive to sunlight.
Handle these plants with care!

Alstroemaria (Peruvian Lily) skin allergy
Leyland cypress Inhalation of smoke or contact with sap. (I have been there—am very allergic to some trees, especially in burning them. Allergy settles in my lungs!) Allergy
Daphne’s D Skin allergy
Dictamnus D Photodermatitis
Dieffenbachia D Skin and eye irritant
Echium Skin irritant
Euphorbia (spurges) sap is a skin irritant in daylight.
Primula obconica German primula D dermatitis
Ruta (Rue) D* Severe skin rashes if handled in sunlight. Skin damage can be permanent.

I have further noticed that some of these effects may be cumulative. My own allergic reactions have been in great part due to excess stupidity. After deadheading spent flowers in the spring and exposing myself to these plant irritants and winter molds that have accumulated on the stems … I then burnt them in piles.

Every spring I came down with lung specific allergy attacks. Burning cedar and cypress’s seem equally bad for this gardener.
Use caution when dealing with any plant you are allergic to!
I make note that this is a listing of some plants that have proven to be a problem to humans. Dogs and cats may have other issues, so please ask your Veterinarian about plant concerns for animals.

Oral Toxins Oral Toxins

O -poisonous. O very serious! D dermal

Aconitum (Monkshood) D O
Aesculus (Horse chestnut) O
Arum (Cuckoo plant) O *
Atropa bella donna (Deadly Nightshaide) O berries
Colchicum (Meadow saffron) O
Convallaria majalis (Lily of the Valley) O
Daphne lauereoloa and mezereum O berries
Datura O
Dieffenbachia (house plant) sap is toxic but usually poisoning occurs when the leaf is chewed. O
Digitalis (foxglove) O
Euonymus O attractive seedpods
Euphorbia O and probably D. Wear gloves when pruning.
Gaultheria mucronata (Pernettya) O Leaves, fruit and nectar are poisonous. berries
Gloriosa superba (Glory Lily) O* tuber looks like a sweet potato
Helleborus O
Ipomoea (morning glory) O* Seed pods
Iris O I suppose I would be most concerned with foetidissima because of its seed heads. Tubers are poisonous.
Laburnum O* Seed pods are the most worrisome potential for poisoning.
Lantana 0* berries are dangerous.
Lupinus (Lupin) O Seedpods are a risk. Large amounts may need to be eaten.
Nerium (Oleander) O* taste is bitter, and often causes vomiting.
Polygonatum (Solomon’s seal) O*
Prunus laurocerasus O All parts especially the seeds
Rhamus buckthorn O All parts. Berries
Ricinus communis (Castor Oil Plant) O* Highly toxic. This plant should not be sold!
Solanum species (Nightshade) OAll parts, leave and unripe berries. Berries can be fatal for children.
Taxus (Yew) O* All parts. Eating the seeds can be deadly!
Wisteria O. All parts especially the seeds and pods.

© by Herb Senft 2008


  1. I have a few that I'd like to add. Japanese anemone, for one. I got some several years ago in an order as a "bonus" and I've been fighting them ever since. Any bit of root left will sprout. The flowers are not worth it. Also, I like shasta daisies, but the way they spread! A really bad one is phalaris, the pink and green striped grass. One friend gave me some (thanks a lot) and another friend recently told me she could not believe she actually bought and planted some. Really hard to get out, it spreads everywhere and the roots go on forever. I think the worst thing about it is that it spreads into the plants that you like and it's difficult to weed out without harming the desirable plants. Also be careful where you plant the ornamental strawberry. At least it's easier to pull.

  2. Thank you Carol,

    I totally agree with the Japanese anemone. One of my customers simply loves it. Her husband and I sneakingly control it.
    Phalaris and many other grasses can be VERY invasive. Planted inside a buried 15 gallon pot should do the trick. I also used it on a floating raft in a pond. Ducks and other birds love to next in it. I do not think that it spreads from seeds, so that is a plus.
    Strawberries. Yes. Variegeted forms less so, but the alpine strawberry and the pink flowered forms can indeed become quite a pest. I continue to pull the plant out where it is not appropriate.
    After selling the latter to many, I now find it to be job security.