(Author’s Note: My first column for the month of May is always about the importance of dandelions as early spring pollinator plants. I repeat this message annually, assuming that the Bangor Daily News acquires new readers each year for both the print and Internet versions of the newspaper. Dandelions flower at a time of the year when few other sources of nectar and pollen are available in many gardens, so I encourage readers to allow at least some of the dandelions on their property to flower for the bumblebees and native solitary bees.)
Much to our delight, dandelions bloom throughout Marjorie’s Garden in the first week of May. Their bright faces greet the burly bumblebee as she emerges from her underground winter nest into the warmth of spring sunlight. And they are there for the emerging solitary bees that shine metallic green and blue as they forage among golden petals.
We value dandelions for their earliness, for jump-starting the colony-building efforts of native pollinators, providing them with a ready source of early pollen. Later, in June and July, these bees and their offspring will be pollinating our tomatoes and cucumbers.
Native bees need the dandelion flowers as an early source of pollen and nectar, but the dandelions do not always need the bees for pollination. Dandelions can produce seeds by apomixis, a process of asexual reproduction in which each resulting seed contains two sets of maternal chromosomes; every dandelion plant produced from such seeds is a clone of the mother plant. The bees, of course, could care less as long as pollen is still produced.
Apomixis is a sensible approach to reproduction in gardens of plenty. When a population is thriving in a particular region, why take chances with sex and risk the introduction of traits that would limit success? Dandelions resort to sex only on the fringes where resources are limited, where introduction of new genes might lead to improved capacity for survival. Thus we notice differences in individual plant height, growth habit, and other characteristics between populations of dandelions. For example, reduced plant height and a more sprawling growth habit are characteristics that favor survival in areas of frequent mowing.
We also value dandelions because they brighten the early spring landscape. Together with the carpets of bluets that flower at the same time, dandelions turn insipid displays of dormant turfgrass into tapestries of color and texture. Should the dandelion flowering period extend into the growing season for the grass, so much the better, for there is nothing less inspiring in the landscape than a broad expanse of uninterrupted lawn.
Consider the impact of dandelions on garden biodiversity. A wide expanse of lawn, managed to exclude all other forms of plant life, has a plant biodiversity of one, the grass species. The chemicals used to control weeds and insects reduce the surrounding biodiversity. On a small scale, a lawn reminds me of another tiresome grass monoculture, the never-ending cornfields of Iowa. The presence of dandelions, however, increases plant species diversity and boosts insect diversity by the number of different herbivores and pollinators. On a single spring day I have stood in the midst of a small patch of dandelions by the porch steps and watched bumblebees, solitary bees, butterflies, hoverflies, other flies, and beetles as they crawl and fly among the flowers. These insects and many others, both adults and larvae, attract birds. Rabbits leave their woodland cover to munch dandelion leaves on the edge of the garden. And, in the absence of the toxic chemicals used to control dandelions, the soil comes alive.
And who can resist picking a dandelion clock, the term used for the head of single-seeded fruits, each attached to its own parachute, and blowing the seeds to the wind? So what if some of those seeds find there way into garden beds? You can pop the seedlings out of the ground as you wander around the garden on sunny mornings planning the day’s garden work.
Yes, I know, dandelions are not native to New England, or North America for that matter, at least not the most regionally common species of dandelion, Taraxacum officinale. Native to Eurasia, this non-native species has followed humans around the world and can even be found in Alaska.
In Alaska’s Denali National Park, dandelions grow in roadside ditches and cut banks, both human-disturbed areas, and there are those who call them invasive. But dandelions do not have what it takes to move from those disturbed areas into wilder areas where they would outcompete native species for essential resources, the defining characteristic of an invasive species.
Across the country, dandelions are recommended as an important early-season pollinator plant by agricultural scientists and farmer support groups. A publication by the Maine Organic Farmers and Gardeners Association (MOFGA), “Bee-Friendly Farming Increases Crop Pollination”, recommends dandelions for attracting native bees to the garden. Dandelions are also recommended by the University of Maine Cooperative Extension as an important pollinator plant. Their list includes the statement that “no plants listed here are invasive exotic species.”
Wherever humans have roamed, dandelions have become naturalized in disturbed areas, including our lawns, their seeds hitching rides on car tires and shoes. Let’s acknowledge which species is the true invasive species. And let us appreciate dandelions for the service they provide in the garden ecosystem and for brightening otherwise desolate landscapes.
Keep the lawn mower in the garage until dandelion seeds fill the air! Better still, turn that front lawn into a pollinator garden, one that includes dandelions, and ditch the mower.