They are not.
I was as surprised as anyone to find the poinsettia’s reputation as a snatcher of young lives is undeserved. Why do we all believe it is so dangerous?
Almost 100 years ago a child died in Hawaii, and someone said she was poisoned by a poinsettia leaf (she wasn’t). Why did they say it? No one knows.
Like other members of the genus Euphorbia (some of which may be growing in your yard right now), poinsettias have a milky-white sap that leaks out wherever the plant is broken or injured.
The sap coagulates at the site of injury, sealing it off and lending its antibiotic properties. It also tastes pretty bad, which discourages ingestion by hungry herbivores . . . and curious toddlers. Eat-anything puppies, however, may eat enough to cause vomiting.
Poinsettia sap is just mildly irritating compared to some of its cousins, which have saps that can blister and blind. However, its sap is still classified as latex – basically water with a complex mix of chemicals that turn to gel or harden when exposed to air – and can be problematic for those with latex allergies. Poinsettias belong to a larger family of plants that include the rubber tree (Hevea brasiliensis), whence comes natural rubber.
Not a flower
The red, white or pink poinsettia “petals” are called bracts, and they are specialized leaves. They serve to guide pollinators to the actual flowers, which are those tiny things in the center of the bracts.
The poinsettia’s flowers are arranged in units called cyathia, and while they are typical of Euphorbias, they’re not much like other flowers we know. Each cyanthium is made up of a single female flower, stripped down to just an ovary (where seeds are formed) and a style that receives pollen. Each female flower is surrounded by several male flowers that are also stripped down to just the necessary part, ie, a pollen-bearing stamen.
Each happy little polyandrous unit is accompanied by a nectar gland that looks like yellow cartoon lips. The nectar’s job is, of course, to entice pollinators to come close enough to move pollen from the stamens to the style.
There is one other thing . . .
The dense, compact little poinsettia plants that fill grocery and drug stores every fall don’t get that way naturally. In addition to genetic manipulation via selective breeding, growers drench the plants and/or their soil with plant growth regulators (PGRs), which keep the stems from growing tall and stringy.
The amount of PGRs that might be present on poinsettia leaves would be much too small to be toxic by ingestion, especially given how bad the leaves taste. It’s probably worth keeping your take-no-prisoners puppy away from them, though, if only for your peace of mind. One of the common PGRs, daminozide, is the infamous Alar that was sprayed on apples until 1989, when a fuss was made about its carcinogenic potential. The concern was probably overblown but it is no longer used on food crops in the US.
Buying and caring
You’ll be attracted to plants with vigorous leaves and bright colors, but also take a close look at the little flowers. If you can see a lot of pollen you’ll know they’ve been blooming for a while, and they won’t stay fresh as long as plants with less mature flowers. When you take them home keep them warm, provide sunlight if possible, and water them before they get completely dry.
Is it worth it to keep poinsettias?
You can try. Poinsettias are perennials, but so many are available every year at such low prices most people treat them like annuals, tossing them in the compost after the holidays. Getting them to “flower” again (in other words, getting the bracts to turn a color other than green) is tedious and labor-intensive, as the amount of light they receive has to be tightly regulated for a number of months. You’re not likely to be successful keeping them as potted plants for next year’s decorating.
You can plant them in your yard if you live in USDA zones 10 to 12 but keep in mind they may grow 8 to 10 feet tall and wide! To do this, keep them in a sunny window, watering when nearly dry, until any frost danger is passed. After the leaves fall off cut the stems back and reduce watering. Plant outside in a sunny, warm spot and feed with an all-purpose fertilizer when new growth starts.