University of Vermont Extension System
Department of Plant and Soil Science

Potentially Harmful Perennials OH 63

Leonard P. Perry, Extension Associate Professor

A subject of increasing concern recently, but one which has existed all along, is that of the harmful nature and potential toxicity of certain perennials. Whether propagating and growing perennials, installing them, or merely retailing them, it's important to know for your own safety and that of your customers which perennials may cause problems. This is especially important in some parts of the country with an increasing number of liability lawsuits, and warnings are increasingly seen in mail order catalogs. The Horticultural Trades Association (HTA) in the United Kingdom has even gone farther in requiring certain warnings to appear on perennial labels and point-of-purchase sales materials, which are given in the table below.

This table listing covers the major perennials which are found in the literature on poisonous plants for humans. Many of these are also listed for animals, although some may be poisonous, either in whole or in part or in other forms (such as boiled hops with dogs), with animals but not humans, or vice versa. This fact should be kept in mind when reading books on poisonous plants. Other perennials are likely toxic in some degree that are not on this list, with so many perennials available. It is likely some persons and not others may have a reaction to certain plants. Some species or cultivars of a genus may be toxic, and not others. Some perennials listed may have the potential to cause toxicities, even though none may have been reported or an improbable amount of the plant or parts would have to be ingested to be harmful or toxic. There are of course other plants such as herbaceous weeds, annuals, tropical houseplants and woody plants which are toxic, and can be found in the following references. Especially if serving the public a firm should have a reference on poisonous plants and number posted of the nearest poison control center.

References on poisonous plants (from which the following table is derived):

Potentially harmful perennials

Scientific name, common name, Toxicity*

Achillea millefolium, Yarrow, Skin irritant in sunlight
Aconitum, Monkshood, CAUTION toxic if eaten (HTA)
Actaea, Baneberry, Harmful or toxic if eaten/skin+eye irritant (berries, roots)
Adonis, Pheasant's Eye, Toxic if eaten
Agrimonia, Agrimony, Skin irritant in sunlight
Agrostemma githago, Corncockle, Harmful if eaten (HTA)
Allium, Onions, Garlic, Skin irritant
Alstroemeria, Peruvian Lily, May cause skin allergy (HTA)
Amaryllis, Belladonna Lily, Harmful if eaten (bulbs)
Ammi majus, Bishop's Weed, Skin irritant in sunlight
Anthemis cotula, Dog Fennel, Skin irritant in sunlight
Aquilegia, Columbine, Harmful if eaten (HTA)
Arisaema, Jack-in-the-pulpit, Harmful if eaten
Artemisia, Mugwort, Skin irritant
Arum, Wild Ginger, CAUTION toxic if eaten/skin+eye irritant (HTA)
Aster, Aster, Daisy, Skin irritant
Atropa, Deadly Nightshade, CAUTION toxic if eaten (HTA)
Baptisia, False Indigo, Harmful if eaten
Calla palustris, Water Arum, Harmful if eaten
Caltha, Marsh Marigold, Harmful if eaten (HTA)
Caulophyllum thalictroides, Blue Cohosh, Harmful if eaten (berries, roots)
Chelidonium majus, Swallow Wort, Toxic if eaten
Cicuta, Water Hemlock, Extremely toxic if eaten
Clematis, Virgin's Bower, Harmful if eaten
Colchicum, Autumn Crocus, CAUTION toxic if eaten (HTA)
Colocasia esculenta, Elephant Ears, Harmful if eaten
Convallaria majalis, Lily of the Valley, CAUTION toxic if eaten (HTA)
Crinum, Spider Lily, Harmful if eaten (especially bulb)
Cypripedium, Lady's Slipper, Skin irritant
Daucus carota, Queen Anne's Lace, Skin irritant in sunlight
Delphinium, Larkspur, Harmful if eaten (HTA)
Dendranthema (not pot mums), Mum, May cause skin allergy (HTA)
Dicentra spectabilis, Bleeding Heart, Skin irritant
Dictamnus albus, Gas Plant, CAUTION skin irritant in sunlight (HTA)
Digitalis, Foxglove, CAUTION toxic if eaten (HTA)
Echium, Viper's Bugloss, Skin irritant (HTA)
Erigeron, Fleabane, Skin irritant
Euphorbia (not poinsettia), Spurge, Harmful if eaten/skin+eye irritant (HTA)
Gaillardia, Blanket Flower, Skin irritant
Galanthus, Snowdrop, Harmful if eaten (bulb)
Gloriosa superba, Gloriosa Lily, CAUTION toxic if eaten (HTA)
Hedera, English Ivy, Harmful if eaten/may cause skin allergy (HTA)
Helenium, Sneezeweed, Skin irritant
Helleborus, Hellebore, Harmful if eaten (HTA)
Heracleum, Hogweed, Skin irritant in sunlight
Humulus, Hops, Skin irritant
Hyacinthus, Hyacinth, Skin irritant (HTA)
Hymenocallis, Spider Lily, Harmful if eaten (bulbs)
Hyoscyamus, Henbane, CAUTION toxic if eaten (HTA)
Hypericum perforatum, St. John's wort, Harmful if eaten (HTA)
Iris, Iris, Harmful if eaten (HTA)
Lactuca, Lettuce, Skin irritant
Lobelia, Cardinal Flower, Harmful if eaten
Lobelia tupa, Devil's tobacco, Harmful if eaten/skin+eye irritant (HTA)
Lupinus, Lupine, Harmful if eaten (HTA)
Lycoris, Spider Lily, Harmful if eaten (bulbs)
Narcissus, Daffodil, Harmful if eaten/skin irritant (HTA)
Oenanthe crocata, Water Dropwort, Toxic if eaten
Ornithogalum, Star-of-Bethelem, Harmful if eaten (HTA)
Pastinaca sativa, Parsnip, Skin irritant in sunlight
Phacelia, Stinging Phacelia, Skin irritant
Physalis, Lantern Plant, Toxic if eaten (especially children)
Phytolacca, Pokeweed, CAUTION toxic if eaten (HTA)
Podophyllum peltatum, May Apple, Skin irritant, toxic if eaten (except fruit)
Polygonatum, Solomon's Seal, Harmful if eaten (HTA)
Primula farinosa, Birdseye Primrose, Skin irritant
Primula obconica, Primrose, CAUTION may cause skin allergy (HTA)
Pulsatilla, Pasque Flower, Harmful if eaten
Ranunculus, Buttercup, Harmful if eaten/skin+eye irritant
Rheum, Rhubarb, Harmful if eaten (uncooked leaves)
Rudbeckia hirta, Black-eyed Susan, Skin irritant
Ruta, Rue, CAUTION severely toxic to skin in sunlight (HTA)
Sambucus. Elderberry, Harmful if eaten (except cooked ripe fruit)
Scilla, Squill, Harmful if eaten (HTA)
Senecio, Groundsel, Toxic if eaten
Solanum, Nightshade, CAUTION toxic if eaten (HTA)
Spigelia, Pinkroot, Toxic if eaten
Symplocarpus foetidus, Skunk Cabbage, Harmful if eaten (leaves)
Tanacetum vulgare, Tansy, Skin irritant/toxic if overdose eaten
Tulipa, Tulip, Skin irritant (HTA)
Veratrum, False Hellebore, CAUTION toxic if eaten (HTA)
Zantedeschia aethiopica, Calla, Harmful if eaten (leaves)
Zephyranthes atamasco, Atamasco Lily, Harmful if eaten (bulbs)
Zigadenus, Death Camus, Toxic if eaten

*HTA=Horticultural Trades Association, United Kingdom, required labeling; skin irritants in sunlight may be seen in references as "photodermititis"; skin irritant is used here to generally refer to any skin reaction; some plants noted in parentheses may have certain parts which are primarily harmful; see other discussion in above text.

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Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. Lawrence Forcier, Director, UVM Extension System, Burlington, Vermont. University of Vermont Extension System and U.S. Department of Agriculture cooperating, offer education and employment to everyone, without regard to race, color, national origin, sex, religion, age, disability, political beliefs, and marital or familial status.

Last reviewed 2/28/97