The common dandelion: more than a week but only part of solution to declining pollinators

·8 min read

A yellow wave is upon us. On Manitoulin Island during the spring months, roadside ditches are lined with cheery marsh marigolds, clumps of yellow daffodils stand tall in residential gardens and dandelions are cropping up everywhere, often covering lawns with their bright yellow flower. While many people see the common dandelion as a pesky invasive weed, others promote it as an important source of early spring nectar for bees and other pollinators. It’s also a source of food and medicine for people.

Dandelions originally hail from Europe but have naturalized throughout most of Canada. The name comes from the French ‘dent de lion,’ meaning lion’s tooth, and refers to its toothed leaves. It is believed that dandelions were purposely brought to North America by early settlers for their medicinal benefits. The plant has been used for over a thousand years by Egyptians, ancient Greeks, Romans and in China for medicinal purposes. Its Latin name, taraxacum officinale, has roots in the Greek words for disorder and remedy; ancient Greeks believed dandelions would cure almost any illness.

Prior to the twentieth century and the invention of green lawns, dandelions were praised in Europe and were considered beloved garden flowers rather than weeds. They were woven into wedding bouquets for good luck and have long been symbols of hope, summer and childhood. Japan had horticultural societies dedicated to dandelions.

Today, however, the common dandelion is often the most unpopular plant in the neighbourhood. Opponents of dandelions say they crowd out native plants, are easily dispersed to other people’s gardens by their fluffy seeds and are difficult to eliminate from lawns and gardens because of their long tap root. “The dandelion is a tap rooted plant. The root is usually six inches long but apparently can reach up to 10 feet,” Claudette Sims with Halton Region Master Gardeners pointed out. “Certainly, some tap rooted plants can act as tillage crops, which are used to break up clay soils by penetrating the compacted layer, creating pore space that allows water and air to penetrate.”

Radishes are a tap rooted plant that have been used to break up surface soil compaction and improve soil tilth, but radishes won’t regrow from the root as a dandelion will. “That would make it challenging, if not impossible, to grow anything else in that area,” said Ms. Sims. “I suppose dandelions could be viewed as good for soils but so are many other plants. There are several native plants that would offer food sources for pollinators and other insects as well as have roots that both stabilize the soil and reach deep into it.”

Karen Stephenson is a writer, researcher, wild food educator and chartered herbalist. She says dandelions play an integral role in maintaining healthy soil. “Dandelions are the prime indicator that the soil is compacted and when soil is compacted it tends to be anaerobic which means there’s a lack of oxygen in the soil. Their role is to basically drill holes with their long tap root. This creates more oxygen which creates more soil microbes. Soil microbes are essential,” she said.

When people introduce chemicals into the soil through the use of herbicides, pesticides and some fertilizers in their quest to get the perfect green lawn, they end up destroying the soil microbes. “They’re killing the health of the soil and those microbes are dying,” said Ms. Stephenson. “Going back to the dandelions, one of the indicators of dandelions being prolific in a certain area is that the soil is calcium deficient. As a gardener, if you want that green lawn putting chemicals on it is not the way to do it. Just mow your lawn and those mowed down dandelion leaves will go into the soil and will provide the calcium that the soil and the grass needs. You have to be patient; this isn’t going to work over a period of a few weeks. We’re talking in terms of a couple years but in turn your grass will become what you wish it to be by leaving those dandelions.”

Sue Meert believes dandelions are a healthy part of shoreline ecosystems. She is a 2021 butterfly ranger and assistant project co-ordinator with Manitoulin Streams Improvement Association. “From our standpoint on stream restoration, preventing erosion is what we do,” she said. “Dandelions have such a deep root base that when they grow on the shorelines they’re helping us do our job. We plant trees and other native species; they all do their part along with native grasses and dandelions.”

Dandelions are medicinal as well as edible and full of vitamins and minerals. Ms. Meert likes to paint, so when she looks at a natural lawn, she’s not seeing weeds. “I love that splash of yellow and seeing the bees and butterflies around. It’s a beautiful picture to me,” she said. “It makes sense to leave some areas for dandelions and other native plants to grow.”

Ms. Stephenson and Ms. Sims agree on the benefits of native plant species. “When people here are describing the perfect green lawn, what are they planting?” asked Ms. Stephenson. “They’re planting grass that is not native to Ontario, it’s native to central United States. It’s not meant to be here and this is why they’re water hogs. They’re fighting constantly to get that perfect green lawn so that’s fighting against nature. Kentucky bluegrass, for example, is not native to this area. We’re going to fight constantly to keep it looking healthy. Work with what is supposed to be here and you’ll have greater success.”

There’s a myth that dandelions are the first flower to bloom, added Ms. Sims. “These dandelion promotions are often an attempt to convince the public that dandelions will save the bees and that is completely false. Our bees are often though of as honey bees but honey bees are a non-native species in Ontario. The bees that are native to Ontario and that have successfully pollinated plants since way before honey bees ever arrived are the ones that are endangered.”

There are over 850 species of native bees in Canada, Ms. Sims pointed out. “It is true that honey bees are often found on dandelions. This is not a surprise as honey bees are also not native to North America. They recognize dandelions as a food source because they evolved with it. We know that native plants and insects have evolved over time to form complex and necessary associations. There are specialist native bees that feed exclusively on the pollen of one species of plant (similar to monarchs, whose caterpillars can only feed on milkweed). Dandelions would not be a food for them. Without the evening primrose, there would be no evening primrose sweat bee. The hind legs of this specialist bee have evolved to be able to collect pollen exclusively from that specific plant.”

Honey bees do forage on dandelions and that may confuse a lot of people who see that and think this may be the best flower available, which isn’t necessarily true, said Sarah Mackell, lead biologist with the Native Pollinator Initiative at Wildlife Preservation Canada. That dandelion may be the only flower available or the first they saw that day. Ms. Mackell is currently breeding bees and has a field team out surveying bees. The project involves research, annual large scale population monitoring, outreach, community science and breeding, with a focus on at-risk bees.

There are generalist native bees who do feed on dandelion but this is only a part of the solution, she explained. “Dandelions are kind of a contentious topic at the moment,” Ms. Mackell said. “They are kind of important but they also aren’t the solution to our issues. They do definitely provide pollen nectar for bees in the early spring but actually, dandelions don’t provide all of the essential amino acids that emerging bumble bees need to reproduce to start their colonies. A lot of studies have shown that if you only feed dandelion pollen to bumble bee there are negative impacts on their reproduction. It’s good that they’re there but it shouldn’t be the only thing provided to them, especially because dandelions are non-native as well.”

“We definitely encourage people to plant native species and ensure there are native plants in the landscape,” she added. “Overall I would say early emerging bumble bees need a varied source of pollen for reproduction and many early flowering native plants provide a more nutritious pollen for them compared to dandelions. They are better than nothing but are not the solution to pollinator declines. We shouldn’t be pushing them as a solution for pollinators. I think it’s an important step but I don’t think it solves pollinator decline or pollinator stressors.”

Pollinator decline, specifically bees, is very complicated, Ms. Mackell explained. There isn’t just one stressor or one thing that’s causing the decline. “There are likely multiple things going on at the same time, for example climate change, habitat loss, pesticides, pathogens is a big one. Definitely, planting natives is good for providing forage for pollinators throughout the season, also making sure there are no periods where they don’t have anything to forage on.”

She believes it’s good to have some dandelions in the lawn. “Lawns don’t have to look perfectly green. Hopefully after a year or so of living with dandelions they can start to think about putting native plants in their yard. Allowing dandelions to remain in the yard is a good start to having people start to think about ecology.”

Lori Thompson, Local Journalism Initiative Reporter, The Manitoulin Expositor

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