The Trouble With Double Flowers (Sorry, Pollinators!)

While we love the beauty of double flowers like hybrid roses, peonies, and coneflowers, compact, frilly blooms make it impossible for pollinators to collect nectar and pollen.

If you are interested in growing a healthy eco-system, learn about all our pollinators (along with bees) and what we should grow to support them.

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Why Double Flowers Are a Problem

If you love growing flowers like I do but also have concerns about the environment, you want your plant choices to be both beautiful and useful.

Flowers provide nectar and pollen in symbiotic relationships with pollinators, getting reproduction assistance in exchange for food. But even if a plant species is native or well-adapted to our area, we may—unknowingly—be growing plant cultivars or hybrids that are of little or no use to pollinators.

So what’s the problem?

Double flowers.

Plants with “double flowers”—what we call flowers that have a lot more petals than average—can be incredibly beautiful but completely (or nearly) useless, offering little or nothing for pollinators. They are all show with little or no substance.

We see double flowers in common plants including roses, peonies, carnations, anemones, camelias, and many others.

A favorite I’ve had in my garden for years are double echinacea (coneflowers), bred both for their double blooms, and deep, rich jewel tones, much different than the pinks found in nature. They look magnificent, but—right nearby—the bees that devote their days to foraging on the native (straight species) coneflowers take no notice of them. They might as well be fake.

Listening to researchers in recent years, I keep hearing the same concern: the more we breed plants away from the color and formation they co-evolved with, the less attractive or valuable they may be to pollinators.

And that’s a big price to pay for some extra frilly blooms.

Contents

• How Double Flowers Form
• Single Flowers Have Problems Too
• Should I Grow Double Flowers
• Historical References
• Resources

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How Double Flowers Form

Nature has always produced some double flowers, which are caused by a genetic mutation. Nearly all of the double-flowered plants you’ll see today are bred for this feature.

The additional petals that make up double flowers are formed from what would have been the flower’s reproductive parts, situated in the middle of the flower.

These extra petals would have been the androecium (male parts) including the stamens and anthers, and the gynoecium (female parts) including the carpels or pistils. Most flowers have both sex parts, while some have one or the other as we discussed here: Do Plants Have Sexes?

But with double flowers, that space is filled with petals, making a dense, fluffy flower.

There may still be some anthers and carpels underneath the petals, but not as many, and they are inaccessible. With much lower pollen and nectar volumes, pollinators are better off using their energy elsewhere.

So, from a wildlife perspective, a double flower is of very little value. And—double whammy—double flowers typically produce fewer (if any) seeds as well.

Single Flowers Have Problems Too

Even without double flowers to contend with, the daily life of a pollinator is not easy. The availability of good quality, easy-to-access pollen and nectar is a sliding scale and single flowers can be duds too.

Nectar production can vary day to day and even hour to hour and differs between plant species and individual plants.

If you’ve ever watched bees, wasps, butterflies, flies, and other pollinators forage, you start noticing all the variations. Even with nectar-rich plants, there may not be much available at that moment or perhaps buddy got there first.

We often think an animal’s persistent visit to a food source indicates they “love it”, but it could actually mean they are struggling to get what they need. A plant can be attractive but offer little or no nutrition. ^[8]

There can also be some intriguing trickery. We did a podcast episode (#318 How Flowers Communicate With Pollinators) discussing how some plants like orchids can deceive pollinators into thinking they’ll be a good source of nectar, only to find nothing there.

So, foraging in general is a mixed bag, but double flowers certainly compound the problem.

Should I Grow Double Flowers?

Assuming you want your garden to be part of the larger ecological network that sustains life, consider what your garden has to offer and how it fits in the bigger picture.

At one extreme, some advise never growing any double flowers because they hurt (or do not help) pollinators.

And, to that point, it does seem counter-productive to further waste a pollinator’s time and energy when a different plant selection could do so much more.

But there are many other things in our gardens that are not great sources of nectar or pollen either and plants can serve many purposes.

Not to say this justifies the double flower choice, but, pollinators have survived for millions of years with all sorts of challenges and imperfections.

A garden exclusively dedicated to double flowers would be highly questionable from an eco-beneficial perspective. But some double flowers should not be a problem, if, overall, the garden and surrounding vicinity is thriving and diverse.

For me, I’m not giving up my few double coneflowers in a sea of diversity (see my garden here), but neither will I plant more of them.

I began gardening choosing beauty or usefulness. Now I see the beauty is the usefulness.

Historical References

What might be the first-ever great book on botany was Enquiry Into Plants, as it is known in English, by Theophrastus, written about 2,300 years ago.

Theophrastus was Greek and a student of Plato’s. Aristotle was his mentor.

In his book, he wrote that:

“Among roses there are many differences…. Most have five petals, but some have twelve or twenty, and some a great many more than these; for there are some, they say, which are even called ‘hundred petalled.'”

Double-flowered roses and peonies were cultivated in ancient China as well.

One step toward an explanation came centuries later with Goethe (1749-1832). Best known as a poet, playwright, and novelist. Faust is his best-known work. He also did some significant work in science.

He wrote a short book (in German) in 1790 called the Metamorphosis of Plants. The very first sentences of the book talk about double flowers:

“Anyone who observes even a little the growth of plants will easily discover that certain of their external parts sometimes undergo a change and assume, either entirely, or in a greater or lesser degree, the form of the parts adjacent to them. So the simple flower, for example, often changes into a double one, if petals develop in the place of stamens and anthers.”

Goethe went on to give an account that we can see as a forerunner to modern models of flower development. Our current explanation for how reproductive organs become petals through mutations requires a heavy-duty understanding of genetics.

For our own plant choices, what we know today is, double flowers can be incredibly beautiful but don’t make much of a contribution in an eco-system, providing little or no value to pollinators.

And if you are eco-logically-minded, usefulness is a more important trait than frilly flowers.

Resources

Read More

1. Welcome Bees—But Don’t Forget These Other Pollinators | Kim Eierman
   Insects are the largest category of animal pollinators. This includes bees, beetles, butterflies, moths, flies, wasps, ants, and mosquitoes. Other pollinators: birds, mammals, and lizards.
2. A Double-Flowered Variety of Lesser Periwinkle (Vinca minor fl. pl.) That Has Persisted in the Wild for More Than 160 Years | Annals of Botany
3. Say It With Double Flowers | Journal of Experimental Botany
4. Native or Exotic? Double or Single? Evaluating Plants for Pollinator-friendly Gardens | Annals of Botany
5. Abnormal Flowers and Pattern Formation in Floral Development | Caltech
6. Genes For Unusual “Flower Within A Flower” Are Identified By UCSD Scientists | Science Daily
7. From Nursery to Nature: Evaluating Native Herbaceous Flowering Plants Versus Native Cultivars for Pollinator Habitat Restoration | Annie White, University of Vermont
8. Flower Power: Cultivars VS Straight Species? | The Humane Gardener
9. Picking Plants for Pollinators: The Cultivar Conundrum | Xerces Society

~Melissa the Empress of Dirt ♛