Out in the Woods
- December 13th 2024
- Out in the Woods
Roadside winterberry in Springvale
Photo: Kevin McKeon
A Feast for the Eyes and the Birds
By Kevin McKeon, Maine Master Naturalist
On late fall and winter walks along many of Sanford’s well-cared-for trails, especially near wetland areas and ditches, we often see the bright red berries of our native winterberry, Ilex verticillata. It’s a popular home-garden shrub too, with many varieties developed for their showy fruit that display color well into winter in our garden and border areas.
Winterberries are actually drupes, or stone fruit, like peaches, plums and olives. Berries have a relatively thin coating around seeds, like tomatoes and blueberries, whereas any fruit with a fleshy outer layer surrounding a hard stone containing a single seed is considered a drupe.
Growing 6 to 12 feet tall, winterberry spread by both seed dispersal and basal shoots — suckers that emerge from the plants’ roots that often generate their own roots and are clones of the parent. Spreading this way results in thick colonies, and the plants can be transplanted to other areas by splitting — digging up and replanting the sucker-based plant. They are a type of holly, which includes up to 600 species of shrubs, trees, and vines worldwide, with about 47 native to eastern North America. And like most hollies, winterberry contain an alkaloid called theobromine, which is also found in chocolate, and has caffeine-like effects on humans. With proper dosage, theobromine can be beneficial to heart health. But due to the relatively high levels of theobromine in winterberry, the plant is considered toxic to humans and horses if eaten, causing stomach pain, nausea, vomiting, dizziness, low blood pressure, blurred vision, and convulsions. The sap and pollen can cause eye irritation and breathing discomfort.
But nature seems to have endowed her wildlife and winterberry to be beneficial to each other by letting her creatures know that the drupes’ toxicity seems to wane with age. So along with their natural resistance, winterberry is a safe — indeed lifesaving — winter food source for many species of wildlife. And as the fruit is eaten, the seeds get dispersed over the landscape to help ensure winterberry’s survival. Over 40 species of birds are known to visit winterberry colonies, along with deer, raccoon, mice, and rabbit. Thoreau wrote about his mice observation, that they “run up the twigs at night and gather this shining fruit, take out the small seeds, and eat their kernels at the entrance to their burrows.”
Winterberry plants are dioecious; a male plant’s pollen is needed to fertilize the female plant so she can produce those bright red fruits. Drupes form on two-year-old wood — twigs that grew the previous year — so it takes two years to produce fruit. The small white flowers produce nectar and attract many pollinators in the spring, and the plant itself supports over 30 species of caterpillars, which are valuable protein food sources for our nesting birds’ chicks. The fruits are not especially nutritious and are fairly low-fat, so are not really relished by our furred and feathered friends, but do provide a needed late winter food source when other foods are scarce. And since they’re often shunned by nature’s critters until late winter, the red beauties tend to persist against winter’s white snow blanket for us to enjoy. Winterberry likes our wet, acidic soil, so consider planting this late winter snack for your local wildlife – and for your eyes!
Editor’s note: Did you see something unusual last time you were out in the woods? Were you puzzled or surprised by something you saw? Ask our “Out in the Woods” columnist Kevin McKeon. He’ll be happy to investigate and try to answer your questions. Email him directly at: kpm@metrocast.net
