IN GOOD THYME Popular holiday plants hide pretty poisons

Decking the halls — and other rooms of our homes — with boughs of holly and greenery is a centuries-old Yuletide custom. Among the traditional plants of this festive season are holly, mistletoe and poinsettia. Although it usually isn’t brought into the house, a winter-blooming plant with a holiday name is the Christmas rose, or hellebore. In addition to being harbingers of the holidays, these plants have a sinister characteristic in common: all of them are poisonous.

English holly (Ilex aquifolium) has been valued for centuries for its dark, glossy evergreen leaves and festive red berries. Therein lies the problem. The pretty berries are attractive to children. The plant contains several toxins that can cause serious cardiac and gastrointestinal problems. According to research published by Cornell University, as few as two berries will cause nausea in a child. When eaten in greater numbers, persistent vomiting and diarrhea follows. It is thought that consumption of 20 to 30 berries may be fatal. Interestingly enough, holly berries are a favorite food of wild birds, and don’t seem to affect them negatively. In fact, the spread of non-native holly in the Pacific Northwest is directly attributable to seeds in bird droppings.

While it’s okay to kiss under the mistletoe, it’s not a good idea to nibble on it. All parts of the parasitic vine, which grows in the tops of trees, contain toxic proteins. Eating the white berries can cause mild to severe stomach pains in children and pets and there are documented cases of fatal poisonings.

Poinsettia (Euphorbia pulcherrima) used to get a really bad rap. However, Poinsettia’s poisonous reputation has improved somewhat in recent years. Current research has downplayed the toxic effects of its milky sap. There also seem to be variables in toxicity between different strains of the plant. It’s still a good idea to keep it out of reach of children and pets, as ingestion causes nausea, burning of the mouth and vomiting, certain to dampen the holiday spirit.


Let’s move outdoors now to an interesting group of plants called hellebores. Members of the buttercup family, they have been familiar to mankind since ancient times. Its botanical name, helleborus, derives from the Greek helein, to kill, and bora, food. Its legendary toxicity was documented by Pliny. In The Canterbury Tales, Chaucer refers to hellebore as a laxative, and the plant was linked to sorcery and witchcraft in the Middle Ages.

In the 21st century, hellebores are known as cold-hardy, shade-tolerant evergreen perennials that bring a touch of color to the garden when almost every other perennial is dormant. The best known species are those called Christmas rose (Helleborus niger) and Lenten rose (Helleborus orientalis). Christmas rose usually produces a pink-tinged white blossom between December and April. Its cousin, the Lenten rose, puts out purplish green or chocolate brown speckled blossoms in early spring. Flowers of both varieties are sometimes seen nodding cheerfully above the snow.

A rhizomatous plant that dislikes having its roots disturbed, it prefers well-drained, moist soil. A good place to plant hellebores is under deciduous trees or in other protected areas, where they will be shaded in the summer and receive lots of light through the winter months. Remember to keep them well watered during the dry season and avoid high nitrogen fertilizers that can burn those sensitive roots. Hellebore will often self-seed. The flowers may not be true to those of the parent plant and are often attractive surprises. The plant reaches about a foot and half in height and grows in clumps.

Deer seem to sense that hellebores are toxic and generally leave them alone. Although substances derived from hellebore rhizomes have been used medicinally through the ages, it’s wise to be cautious with the Christmas (and Lenten) rose. Gardeners with hypersensitive skin may contract dermatitis upon exposure to bruised roots, leaves, stems and flowers, and ingestion can bring on symptoms ranging from tingling mouth and throat to death.

As with all potentially dangerous substances, exercise caution, especially where children and pets are involved. If someone has been poisoned, immediately call 911. The Washington Poison Center hotline number is 1-800- 222-1222. If you suspect an animal has been poisoned, contact your veterinarian ASAP. The American Society for Prevention of Cruelty to Animals (ASPCA) maintains a 24/7 veterinarian-manned poison information hotline, 1-888-4ANI-HELP, 1- 888- 426-4435.

Garden questions or comments? Call 675-6611 or e-mail Mariana Graham is a WSU-certified Master Gardener and member of Garden Writers Association of America.

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