Annual flowers are more popular with bees than scientists realized

Flowers that you have to replant each year are some of the most popular. You'll find pansies and petunias in hanging pots along busy roads, filling public garden beds in parks and outside gardeners' homes.

They're beloved because they're so beautiful, with full, colourful petals - and they can stay that beautiful the entire season, so a gardener knows what their space will look like from May until Octo‐ ber.

Despite all the diversity in colour and species, entomol‐ ogist David Smitley from Michigan State University says annual flowers are thought of as a "pollinator desert."

Bees don't visit them for their nectar and pollen as of‐ ten as they frequent perenni‐ al flowers like black-eyed Su‐ sans (Rudbeckia fulgida). That's a problem, because pollinators allow plants to thrive and play a critical role in the ecosystem we all de‐ pend on.

But according to Smitley's research published today in the Journal of Economic En‐ tomology, some annual vari‐ etals, like the Cocktail Brandy begonia, might be more pop‐ ular among pollinators than scientists realized.

Eco-conscious Canadians who want to plant annual flowers in their garden don't need to go cold turkey; in‐ stead, Smitley said he hopes people will make a small change by choosing annual varietals that will feed the bees and their other local pollinators.

But finding those varietals may prove to be a challenge.

Why pollinators are a priority

Pollinators are important to our ecosystem because they let "plants have sex," says Ja‐ son Gibbs, an entomologist at the University of Manitoba who helped to identify the pollinators that visited Smit‐ ley's annuals.

"Plants being able to re‐ produce is the foundation of basically all terrestrial ecosystems," Gibbs said.

Plants absorb energy from the sun, then are eaten by the earth's creatures, which in turn are eaten by bigger creatures and so on.

None of that could happen without pollinators.

This cycle works great if everything is in abundance, but there has beengrowing concern about the decline of wild bees (those that aren't managed by beekeepers) in Canada, due a range of fac‐ tors, including habitat loss from climate change and agricultural land use prac‐ tices.

Though Gibbs says we're "in the dark about how well" 90 per cent of the roughly 900 native bee species are doing, there are some species that are known to be in decline, or have gone missing entirely.

"The classic case in On‐ tario is the rusty-patched bumblebee, Bombus affinis," Gibbs said. "Which I don't think anyone's actually seen for a decade or more."

Without pollinators, crops will yield less, trees and bushes can't grow and biodi‐ versity (and all plant health, by extension) will suffer.

Pollinators are smart. They assess how much nec‐ tar and pollen a flowering plant provides and will re‐ member the good and the bad flowers alike. That's why it's so important that the flowers they can reach are full of pollen and nectar.

"The classic example I al‐ ways think of is a wild rose,"

Gibbs said. Wild roses have loose petals and the pollen is clearly visible. Cultivated roses are so full of petals that none of the valuable re‐ sources are visible to a polli‐ nator.

Alan Sullivan, an adjunct professor in the department of plant agriculture at the

University of Guelph, has made it part of his life's work to breed flowers. He ex‐ plained that "prioritizing" long-lasting and colourful flowers through breeding can take resources like sugar away from parts of the plant meant for pollinators, like the flower's nectaries.

Annuals that attract pollinators

The pollinator study evalu‐ ated six species of annual flowers that made up 46.6 per cent of garden centre flower sales in the U.S.: petu‐ nias, impatiens, begonias, geraniums, pansies and New Guinea impatiens. There were three to six varietals of each species.

The varietals in the study that were most highly visited by pollinators could compare to marigolds - usually consid‐ ered reasonably popular with pollinators - Smitley said.

The top four were the be‐ gonia varietals called Cocktail Brandy and Ambassador

Rose Blush, and the impa‐ tiens varieties called Accent Coral and Super Elfin XP White. But even if gardeners know the best varietals, Smitley said that finding them in garden centres may be a problem.

He said the first thing to know is the correct name; each flower has a common name, a scientific name, and a varietal's name, such as marigold (Tagetes patula) Alumia Vanilla Cream. Smitley also suggested famil‐ iarizing yourself with the brand that owns the varietal and even bringing home a few different varietals to see which ones your local pollina‐ tors prefer.

Smitley said breeders could make this all easier for consumers if they docu‐ mented a varietal's attractive‐ ness to pollinators and made that part of the labelling. Part of his work was to show breeders how to record that information.

"It's not that difficult. Plant breeders collect all kinds of data," he said. "They've already found out that by marketing these an‐ nual flowers as being at‐ tracted to pollinators really increases sales."

Sullivan said that breed‐ ers could select for plants at‐ tractive to native pollinators, but he wasn't sure if they would, saying that it would be "very labour intensive" and "time consuming."

Should you abandon an‐ nuals?

Though it identified that some annuals attract more pollinators than others, Smitley and his team's evalu‐ ation ultimately found that annual flowers were not a "a good choice for the purpose of attracting and supporting pollinators."

But Smitley said he's more interested in focusing on small improvements garden‐ ers could make, not convinc‐ ing them to abandon annu‐ als.

"We know already that most people are not going to give up their annuals, be‐ cause they just love them," Smitley said. "They're so beautiful, and we don't have anything as beautiful as they are that is also really attrac‐ tive to pollinators."

Sullivan agreed that annu‐ als still have a role to play in the ecosystem.

"Studies have shown that they do provide a food source," he said. They can help "carry over" the pollina‐ tors during times when perennials are not flowering and, in urban areas, annual

flowers are better than no flowers at all.

But he said other plants can be more valuable to polli‐ nators. Native plants, which Sullivan studies, are useful because the native pollina‐ tors are familiar with them already.

Gibbs also emphasizedthe importance of native plants for the pollinators.

"My mantra is: native plants for native bees," Gibbs said. "That's the best thing that you can do, from a polli‐ nator perspective, is plant native flowers."