What you see: A dried out, papery bit or husk stuck to your blueberry.
What it is: Petals! The corolla tube, if you want to be fancy about it.
Eat or toss: Pull off the “tube” and eat the berry!
The brown papery things attached to your blueberry are probably petals!
All blueberries start out as flowers. At the base of each flower is a small ovary that, if all goes to plan, will swell into a sweet fruit with tiny seeds tucked inside. Once pollination happens, the flower has served its purpose and eventually falls off. (Scroll to figure 24.17 in this book for a nifty diagram of how it all works.)
Or, at least, the flower is supposed to fall off. Sometimes the petals stick around and dry into husks like the ones you see in the images in this post. It doesn’t mean anything is wrong with the rest of the berry. Just pull off the petals and enjoy as usual. And keep reading because blueberry flowers and pollination are fascinating!
Blueberry flowers are bell shaped
Blueberry flowers are bell shaped, which explains why the dried out petals have a deflated windsock look to them. Here are some freshly bloomed blueberry flowers:
In the spring, these flowers attract bees with their fragrance and promise of sweet nectar. The distinctive bell shape protects the inner fruit-and-seed-making parts and makes sure the bees get the job done right.
“It’s there to make it hard for the bee to get to the nectar without pollinating the flower,” said Mark Longstroth, a retired small fruit educator at Michigan State University. “The flower is best pollinated by bumblebees that will shake the flower and cause the pollen to fall out of the flower and pollinate the berry.”
Blueberry flower petals typically fall not long after pollination has occurred
Most blueberries drop their petals soon after pollination.
“We have this saying that if they shed the petals really fast, that means that they’re getting good pollination and if they don’t shed the tubes very fast, that means pollination is poor,” Longstroth said. “Up here in Michigan where we grow northern high bush [blueberries], they shed the petals pretty quickly…we will come into the field and the ground will just be covered with those petal tubes.”
Plants, such as blueberry bushes, follow a standard protocol when they need to shed things like leaves or flowers. The attaching cells (i.e. those holding the petals on) deliberately die. That line of dead cells is called the “abscission zone.”
But the berries pictured above somehow didn’t get the message.
(At least they’re not alone; we’ve also written about abscission goofs in this post about potatoes with stems).
Longstroth said clingy petal tubes are relatively uncommon, but can be associated with poor pollination. He also said that, over decades of blueberry breeding, the trait of reliable flower abscission was probably not prioritized in the particular type of blueberry bush that these fruit came from.
Blueberry pollination is pretty fascinating!
Before we go, here are some fun blueberry pollination facts:
- Once a blueberry is pollinated it sends a signal to the rest of the plant saying “Hey! I’ve been pollinated, send some food!”
- For that reason, the first berries to be pollinated are usually the biggest.
- Berries that aren’t pollinated will either fall off the bush before developing, or just never grow very big.
- Blueberry pollen is sticky and tucked away inside the flower’s anther. While some plants rely on the randomness of wind for pollination and have loose, easily liberated pollen, blueberry have evolved to produce less dispensable stashes of pollen that are energy-intensive to make and therefore tightly guarded so the pollen doesn’t go to waste.
- A bumblebee’s buzz isn’t just a cute sound; their vibrating wing muscles help knock the hard-to-access pollen loose, sometimes releasing a cloud of it. Bumblebees eat the pollen, but it also sticks to their fuzzy bodies, where it fertilizes flowers when they land on the next bush.
- Bumblebees more effectively pollinate than honeybees who can’t “buzz pollinate.” While farmers can hire a crew of honeybees to be trucked in to pollinate their blueberries, bumblebees are wild so farmers just have to hope that they buzz on by. Support your local wild bee population by planting a pollinator friendly garden!
- Mark Longstroth. Retired Small Fruit Educator. Michigan State University Extension.
- Where did all the blueberries go? Mark Longstroth. Michigan State University Extension – November 20, 2018.
- No Buzz, No Problem: Study Shows How Honey Bees Pollinate Blueberries. John P. Roche, Ph.D.. Entomology Today. Dec. 7, 2018.
- The Secret to Better Berries? Wild Bees. By BRIAN OWENS AND BASIL WAUGH. November 28, 2018. Gund Institute for the Environment. University of Vermont.
- Without Buzz Pollination We Wouldn’t Have Blueberries. Dickinson County Conservation Board. June 4, 2018.
- Blueberry Pollinators. Entomology – Insect Biology & Management. North Carolina State University Extension.
This post has been updated to correct an error: Cold springs can cause blueberry leaves to have more purple coloration (not flowers, as originally stated).