11 April 2023

During February’s heat wave I was sure Spring would be extremely early this year in Pittsburgh. Then temperatures dropped in March and everything paused. Yesterday the flowers on this red maple were giving way to seeds while the leaf bud was opening. Is this normal for early April? It’s time for a Spring checkup. Where are we now?

Spring’s progress is easy to see in this USA National Phenology Network animation. Leaf out raced northward in February producing dark red-brown in the places with an earliest Spring on record. In mid-March the racing stopped and gave way to paler red across PA and New York state. But what’s the dark blue in Kansas and the Southwest? It’s a very late Spring.

[As of 10 April 2023] Spring is 11 days late in Denver, CO, 2 days late in Chicago, IL, and 2 days early in Albany, NY. The West is mostly late. Yakima, WA is 12 days late, Boise, ID is 20 days late.

— USA NPN: Status of Spring as of 10 April 2023

Most of Pennsylvania is close to normal compared to baseline years 1981-2015. Pale green is OK. Dark green is not. Southcentral and southeastern PA were off-the-chart early.

As you can see by the splash of color on the map, bush honeysuckle, the Spring leaf out indicator, has finished in Pennsylvania. You can follow the progress of spring blooms and check on the rest of the country at USA National Phenology Network.

(photo by Kate St. John, maps from USA National Phenology Network)

29 March 2023

This is the time of year when invasive plants sprout and bloom before the natives, particularly lesser celandine (Ficaria verna), a member of the Buttercup family with succulent leaves and bright yellow 8-12 petal flowers.

According to invasive.org, lesser celandine prefers sandy soil in low open woods, floodplains, meadows and waste places. It spreads easily through tubers and tiny bulblets so a scouring flood or digging in its vicinity, including digging animals, spreads it to new sites. It also thrives because it’s poisonous and deer don’t eat it.

I usually find lesser celandine blanketing floodplains including those at the Monongahela River at Duck Hollow — where it’s already in bloom — and Chartiers Creek at Boyce Mayview and Wingfield Pines.

Blanketing is what makes it invasive. Native spring ephemeral flowers need unobstructed sunlight to complete their life cycle but lesser celandine leafs out early, blankets the ground and shades the natives before they can make a start.

When I was learning to identify plants I used to confuse it with the native plant marsh marigold (Caltha palustris).

Penn State Extension explains the difference between them here but the biggest hint is this: If the plant is carpeting the ground and blooming in March or early April, especially on a floodplain, you can bet it’s lesser celandine.

p.s. Learn more about invasive plants in Pennsylvania at DCNR’s Invasive Plant Fact Sheets at https://www.dcnr.pa.gov/Conservation/WildPlants/InvasivePlants/InvasivePlantFactSheets/Pages/default.aspx

(photos by Kate St. John and from Wikimedia Commons)

11 March 2023

After a very warm February, with some days reaching 20° to 26°F above normal, the weather returned to expected March temperatures this week and our Too Early Spring hit the Pause Button.

The city’s Urban Heat Island still prompted non-native ornamental plants to bloom including crocuses above and forsythia below.

Garlic mustard came up in Schenley Park.

Native trees, like this sycamore in Schenley Park, waited for warmer weather while non-native willows turned yellow such as the willows at bottom right (perhaps Salix babylonica).

But there are better things to look at. Last Sunday the Botanical Society visited the Otto and Magdelen Ackerman Reserve in Westmoreland County where we found yellow corydalis (Corydalis flavula) poking up among the fallen leaves. No flowers yet.

Plus two impressive fungi on fallen trees.

By the way, don’t forget that Daylight Saving Time begins tonight in most of the U.S. It’s time to Spring Forward.

(photos by Kate St. John, .gif from Wikimedia Commons)

9 March 2023

On Monday 6 March 2023, Fran Bungert sent me an email to say that she saw snow trillium blooming at Cedar Creek Park the day before. She added that 5 March is the earliest she’s ever seen it bloom.

In my experience snow trillium (Trillium nivale) is usually the earliest spring ephemeral in southwestern Pennsylvania, traditionally blooming in late March or early April. The flowers persist for about four weeks so my observations circled below are not necessarily first bloom date. Nonetheless Fran’s 5 March observation in red is the earliest ever!

Inspired to see the flowers I visited Cedar Creek on Tuesday afternoon. Before I reached the snow trillium hillside, I found evidence of flash floods that cut the creek bank. It was a brown landscape compared to what I see in April.

Snow trillium dotted the hillside but blended into the fallen leaves because the white flowers looked like splashes of sunshine. How many flowers do you see in this photo?

The flowers were at various stages from barely to fully open, at top.

I found harbinger of spring (Erigenia bulbosa) leaves but no flowers.

As of 7 March only the snow trillium was blooming at Cedar Creek.

(photos by Kate St. John)

p.s. For my own notes, here’s a list of blogs that indicate when I saw snow trillium:

• 27 March 2011
• 3 April 2013
• 29 March 2015
• 27 March 2016
• 11 April 2018
• 6 April 2019
• 3 April 2020

8 March 2023

North American wildflowers face many threats to their existence including habitat loss, deer overpopulation and pollinator declines but there is another threat we didn’t see coming until now. As the climate heats up North American spring ephemerals will have no time to bloom and store food for the coming summer. Their existence is threatened by the Too Early Springs of climate change.

Forest wildflowers bloom before the trees leaf out because they are in a race to gather as much sunshine as possible before the canopy closes. When the trees reach Full Leaf the flowers stop blooming.

Wildflowers in deciduous forests often rely on leafing out before the canopy to create 50-100% of their annual carbon budget. Lead author and Carnegie Museum of Natural History postdoctoral research associate Dr. Benjamin Lee describes it “as if a person were to eat all the calories they needed for a year in the first three weeks.” 

— Climate Change Threatens North American Wildflowers

Ideally, wildflowers would merely advance their blooming schedules and all would be well but the study published last December in Nature Communications shows otherwise. Using herbarium specimens in North America, Europe and Asia, researchers compared wildflower blooming times and tree leaf out dates for the three continents.

Blooming early works in Europe and Asia because those trees leaf out later anyway. But in North America the trees and flowers use the same temperature trigger. We had a real life example of this in Pittsburgh in March 2012 when temperatures stayed in the 60s to 70s for at least two weeks. In that Too Early Spring everything happened at once.

I visited Barking Slopes on 25 March 2012 and I found both early and late spring wildflowers in bloom: Bloodroot (Sanguinaria canadensis) which normally blooms in late March or early April and large-flowered bellwort (Uvularia grandiflora) which normally blooms in late April.

The trees were leafing out, too.

June weather in March? What could go wrong?

Fewer spring wildflowers in the future.

Read more about the Too Early Spring of 2012 below. Will it happen this year? Only time will tell.

(photos by Kate St. John, diagram from Wildflower phenological escape differs by continent and spring temperature)

p.s. The time gap between bloom-time and leaf out is called the “wildflower phenological escape” hence the study’s name.

6 March 2023

This winter has been so warm in Pittsburgh that flowers bloomed and plants leafed out in February. Spring is early, but how early?

Some years I photograph bush honeysuckle’s early leaves and I can tell you that leaf out this spring is 23 days earlier than in 2015. But that’s only one year.

The USA National Phenology Network (USAnpn.org) tracks the progress of Spring using two indicators, bush honeysuckle and lilac leaf out and blooming times, and then compares them to the average in 1991-2020. The Spring Leaf Index Anomaly map for 4 March 2023 shows that this spring is astonishingly early.

The darkest red indicates 20+ days ahead of schedule. USAnpn called out a few examples in their 27 February report:

[As of 27 February 2023] Oklahoma City, OK is 9 days early, St. Louis, MO is 16 days early, and New York City is 32 days early. Phoenix, AZ is a week late. Seattle, WA is a week early.

— USA National Phenology Network — Status of Spring, 27 Feb 2023

How often does this anomaly happen? The darkest green on the map below shows that this is the earliest spring ever recorded in New York City while purple indicates the latest spring ever seen in southeastern Arizona.

Arizona might be even later now. Here’s snow in Tucson last Thursday morning just after dawn.

Click here to watch an animated map of spring’s advance through 4 March 2023.

(photos by Kate St. John and Ramona Sahni, maps from usanpn.org)