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Phenology Report: Sluggish spring slowly surfacing

 A graphic comparing leaves of trembling and big-tooth aspens. Trembling aspens have leaves with lots of small serrations on the edges, while bigtooth aspen leaves have much larger gaps between pronounced serrations. The left image is of a green leaf with red stem. the base of the leaf is nearly as wide as the leaf is long, and the tip comes to a point. The leaf edges are lined with many small serrations. The image is captioned "Trembling aspen leaf." The right image is of a yellow leaf on the lying on the ground. It has a similar shape to the trembling aspen leaf, but has just 7-8 serrations per side, and the serrations are much larger. It is captioned "Bigtooth aspen leaf".
Sarah Mitchell
A graphic comparing leaves of trembling and big-tooth aspens. Trembling aspens have leaves with lots of small serrations on the edges, while bigtooth aspen leaves have much larger gaps between pronounced serrations.

Despite the surprising resilience of Old Man Winter, spring is resolutely making its way across the state.

To begin this week’s Phenology show, John Latimer harkens back to the blast of summertime weather we enjoyed around April 12. It was followed by a heavy, wet snow that dumped 5.5 inches of snow at John’s house, which melted over the course of last week. It didn't take long for another snowstorm to hit, leaving 6 inches of snow.

Do you have observations to share? We’d love to hear from you! Get in touch with me (, John Latimer (, or text "phenology" to 218-326-1234.

Watch your buddies

During the initial warm spell, one of John’s silver maple trees broke bud. The next day, it was in full flower. By the third day, it was completely done — John found the male flowers were no longer dropping pollen. The cold snap killed off the male flowers, and John expects they will fall from the tree this week.

An intersex cluster of maple tree flowers. Maple trees are normally dioecious, with male and female flowers on separate trees. The image shows a cluster of six flowers. Two of them have long white stamens with pollen-bearing clusters at the end. These are annotated with "Male flowers (with stamens)". Four of the flowers lack these long white parts, and instead have short red pistils.  These are annotated "Female flowers (with pistils)". The image is captioned "Intersex maple tree".
John Latimer
An intersex cluster of maple tree flowers.

Some of the female flowers froze during the cold snap, but others hadn’t opened their buds yet. Those survived the cold snap but may not get pollinated due to the dearth of pollen-producing flowers.

John’s silver maple tree is uncommon. Most maple trees are dioecious, meaning males and females are separate individuals. However, John's tree has a mix of male and female branches, and even has one flower cluster with both male and female flowers appearing within centimeters of each other.

John’s red maples haven’t flowered yet, though the buds are swollen. On average, they flower around April 19. Historically, they flowered on May 8, 2013 (the latest on record), May 7, 2022 (last year), and March 24, 2012 (the earliest on record).

A close-up of an American hazel branch shows the male and female flowers against the backdrop of a human palm. The twig has small hairs on its bark, distinguishing it as an American Hazel. Beaked hazels lack those hairs. A catkin hangs below the branch. It is about an inch long and has small green scales with brownish edges. The catkin has an arrow pointing to it from the text "Male flowers (catkin). Along the twig are two small bud-like protrusions with tiny red spikes poking out of their tips. These have arrows pointing to them from text saying "Female flowers". Another arrow points to the little hairs on the stem: the arrow starts at the text "Tiny hairs distinguish American from beaked hazel". The image is captioned "American hazel".
Sarah Mitchell
A close-up of an American hazel branch shows the male and female flowers. The twig has small hairs on its bark, distinguishing it as an American Hazel. Beaked hazels lack those hairs.

Hazels need a close look

Like the silver maple, the hazel shrubs flowered during the warm spell. The male flowers, which are found inside of long catkins, are most noticeable. As the catkins elongate and open, a slight breeze or brush of a passing hand will elicit a puff of pollen.

The female flowers are more surreptitious. On close inspection, they can be found near the male catkins by looking for a bud-like structure with a little red “hat.” The red “hat” is formed by female pistils — the ovary-containing and pollen-capturing structures of the female flower.

After the cold snap, John found both healthy female hazel flowers and ones killed by the cold. Healthy flowers had vibrant red colors, while frozen ones are bluish-purple.

Last year was a particularly productive year for hazelnuts, so John suspects the harvest will be poorer this year regardless of the number of flowers affected by the cold. Some of them may recover and produce hazelnuts, but we’ll have to wait and see.

Spending some time with an aspen

Aspens are members of the willow family. Most willows produce fuzzy flowers like those found on the aspen, or (more famously) the pussywillow. The male aspen flowers are now very fuzzy and 2-3 inches in length. John hasn’t been able to knock any pollen out of them. He suspects they’ll begin to fall off the tree in the next week, after they’ve finished dropping pollen.

The female aspen flowers are also beginning to elongate. John found one with 1- to 1.5 inch-long flowers. Once fertilized, these flowers turn green. From afar, this makes a female aspen tree look like it’s leafing out, when in fact it’s just covered in these green fertilized flowers.

Trembling aspen leaves typically emerge around April 30. That’s highly unlikely this year. The latest leaf-out John’s recorded was May 17, 2014, and the earliest was April 2, 2012. Last year, leaf out occurred on May 13.

Aspen leaves emerge

The bigtooth aspen leafs out later than the trembling (or quaking) aspen. Its leaves typically emerge around May 17, 18 days later than the quaking aspen’s leaves. In years when spring comes late, the gap between leaf-out dates shortens.

Last year, for instance, there were only 12 days separating quaking aspen leaf-out (May 13) from bigtooth aspen leaf-out (May 25). The earliest leaf-out for the bigtooth aspen was on May 2, 1989, and the latest was May 27 in 2004 and 2008.

This year, the aspens have just begun to set their flowers, and there is no sign leaf-out will occur anytime soon. John suspects the quaking aspens will leaf out sometime around the first week of May, unless we get some surprising weather between now and then.

As always, the more eyes we have on the phenology of the state, the better! If you have aspens near you, keep an eye on them and let us know what you find.

Canada fly honeysuckle with leaves and flowers. The image shows a twig with green leaves and a pair of small yellow flowers. the leaves are oval-shaped, about two inches long, and look soft. The flowers share a stem, which splits in two at the base of the flowers. The flowers are trumpet-shaped and are a pale yellow color. the image is captioned "Canada fly honeysuckle".
iNaturalist user sophiamunoz
Canada fly honeysuckle with leaves and flowers.

Spring takes its sweet time

Another plant John’s monitoring is the Canada fly honeysuckle. It’s a little bush that grows in the forest. It doesn’t grow very tall and has opposite branches. If you find one, take a look at the buds: right now, they’re twice the size they were during winter. They’ve developed a green-and-purple color.

These plants are one of the earliest to leaf out in the forest, making them easily distinguishable in the spring! If you take a close look, you’ll find paired yellow trumpet-shaped flowers.

John is still waiting to hear the grouse drumming, although his friend Dallas heard them in Akeley. John’s also hoping to hear the first wood frog. Typically, they begin calling around April 17. Last year, they didn’t call until May 3. The latest on record was May 6, 2013, and the earliest was March 21, 2012.

The overall message of John’s observations is pretty unambiguous: it’s a late year and may even make the list of top-five latest years on record.

Crooked Lake is still iced over. John has been following John Downing’s method for predicting ice-out date, and his optimistic point total is 184 and the pessimistic total is 170. (Points are calculated based on the average temperature for each day. A point is added for each degree above zero, and the totals for each day are added together. Once the total reaches 220, there’s a 50/50 chance the ice is gone.)

Based on these predictions, a listener wrote in to predict May 3 would be the ice-out date. John isn’t so courageous as to make a definitive guess, but he’s hoping it will be soon!

That does it for this week! For more phenology, subscribe to our Season Watch Newsletter or visit the Season Watch Facebook page.

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

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Charlie Mitchell (she/they) joined the KAXE team in February of 2022. Charlie creates the Season Watch Newsletter, writes segment summaries for the website, and coordinates our Engaging Minnesotans with Phenology project. With a background in wildlife biology, she enjoys learning a little bit about everything, whether it's plants, mushrooms, aquatic invertebrates, or the short-tailed shrew (did you know they can echolocate?).