Category Archives: Phenology

Seen This Week

Star magnolia in bloom, Schenley Park, 27 March 2023 (photo by Kate St. John)

1 April 2023

Welcome to April! Last month brought flowering trees, frost damage, more flowers and early leaf out.

The star magnolia (Magnolia stellata) above was looking good on 27 March but the one below bloomed too early on Pitt’s campus and sustained frost damage.

Frost damage on a star magnolia, Univ of Pittsburgh campus, 22 March 2023 (photo by Kate St. John)

This honeybee didn’t care about the brown petals. She probably flew in from The Porch beehives across the street.

Honeybee at frost-damaged star magnolia, Univ of Pittsburgh, 22 March 2023 (photo by Kate St. John)

Non-native flowers are blooming. Eyebright (Euphrasia sp) popped up in the grass at Frick.

Eyebright in Frick Park, 22 March 2023 (photo by Kate St. John)

Purple dead-nettle (Lamium purpureum) bloomed before the frost and still looked good on the 29th, here with chickweed (Stellaria media) in a Shadyside front yard.

Purple dead-nettle and chickweed, 29 March 2023 (photo by Kate St. John)

Meanwhile leafout is already underway. Bush honeysuckle had leaves on 18 March.

Bush honeysuckle leafout in Schenley Park, 18 March 2023 (photo by Kate St. John)

And by the time I noticed this yellow buckeye (Aesculus flava) in Schenley Park, it was already well beyond first leaves. Two photos show the same branch two days apart, 28 and 30 March. Last year, yellow buckeyes were still in bud on this date.

Meanwhile our trees are in for too much excitement today with high winds gusting to 60 mph. We expect downed trees and power outages in our future.

Batten down the hatches, Pittsburgh!

(photos by Kate St. John, maps from @NWSPittsburgh)

Invasive Lesser Celandine

Lesser celandine at Duck Hollow, 23 April 2019 (photo by Kate St. John)

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, 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.

Lesser celandine at Boyce Mayview, 15 April 2015 (photo by Kate St. John)

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).

Lesser celandine (left), Marsh marigold (right, photo from Wikimedia Commons)

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

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

Spring On Pause + Spring Forward

Crocus in Shadyside garden, Pittsburgh, 9 March 2023 (photo by Kate St. John)

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.

Forsythia in bloom, 4 March 2023 (photo by Kate St. John)

Garlic mustard came up in Schenley Park.

Garlic mustard, 5 March 2023 (photo by Kate St. John)

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).

A shadow of the Panther Hollow Bridge bisects this view of a sycamore in Schenley Park (photo by Kate St. John)

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.

Leaves of yellow corydalis, Ackerman Reserve, 4 March 2023 (photo by Kate St. John)

Plus two impressive fungi on fallen trees.

Armallaria formerly hidden under bark, Ackerman Reserve, 4 March 2023 (photo by Kate St. John)
Are these turkey tails? Ackerman Reserve, 4 March 2023 (photo by Kate St. John)

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)

Too Early Spring: Snow Trillium

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!

Snow trillium observed blooming at Cedar Creek, Kate St. John’s selected years 2000-2023 (calendar image from

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.

Cedar Creek and streamside trail, 7 March 2023 (photo by Kate St. John)

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.

Snow trillium at Cedar Creek, 7 March 2023 (photo by Kate St. John)

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:

Wildflowers Threatened by Too Early Spring

Large-flowered Trillium, Barking Slopes, blooming on 25 March 2012 (photo by Kate St. John)

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.

Bloodroot and bellwort both blooming at Barking Slopes, 25 March 2012 (photos by Kate St. John)

The trees were leafing out, too.

Leaf out on 25 March 2012 at Barking Slopes (photo by Kate St. John)

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.

How Early Is Spring This Year?

Honeysuckle leaf out 23 days apart, 2015 vs 2023 (photo by Kate St. John)

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 ( 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.

Spring leaf out anomaly (honeysuckle), 4 March 2023 (map from

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.

Spring Leaf Index Return Interval, 5 March 2023 (map from

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

Snow in Ramona Sahni’s Tucson backyard just after dawn on 2 March 2023 (photo by Ramona Sahni)

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

Seen This Week

Flowering cherry, Pittsburgh, 1 March 2023 (photo by Kate St. John)

4 March 2023

This week the weather stayed above freezing with an extraordinary high of 72F on 1 March. The plants and trees responded by bursting into bloom and leaf. Pictured here are:

  • A flowering cherry tree in Shadyside, 1 March
  • Coltsfoot in bloom at Moraine State Park, 1 March
  • Hairy bittercress blooming in Shadyside, 2 March
  • London plane tree seed balls disintegrating (a spring thing), 27 Feb
  • Honeysuckle leaf out, 2 March.

A week ago my photos of blooms, buds and leaves were 4 weeks earlier than last year. When I get a chance I’ll see if spring is still running four weeks ahead of schedule.

Coltsfoot blooming, Moraine State Park, 1 March 2023 (photo by Kate St. John)
Hairy bittercress blooming, 2 March 2023 (photo by Kate St. John)
London plane tree seed ball disintegrating, 27 Feb 2023 (photo by Kate St. John)
Honeysuckle leafing out, 2 March 2023 (photo by Kate St. John)

Now that the plants are waking up for spring Pittsburgh’s deer (over)population is finding more to eat. In front of Phipps’ Botany Hall I found a side-by-side example of yews, a favorite deer winter food, protected and unprotected from deer browse. One bush has no protection, the rest were wrapped in plastic fencing(*). You can already see the difference.

(photos by Kate St. John)

(*) The protected yews were wrapped on 15 December 2022 so, at the time of the photo, the unprotected yew was showing 10.5 weeks of deer browsing.

Seen This Week

Woodland crocus or Tommasini’s croscus, 21 Feb 2023 (photo by Kate St. John)

25 February 2023

For seven days this week the temperature stayed above freezing and hit 71 degrees F on Thursday. At 26 degrees above normal, flowers opened on plants and trees.


My favorites were the early crocuses. Native to Bulgaria, Hungary, Albania and the former Yugoslavia, these woodland crocuses (Crocus tommasinianus) are often seen in gardens but someone in my neighborhood planted them in a grassy front yard. Because the flowers bloom before the grass grows they are in no danger of being mowed.

Tomasini’s crocuses blooming in the grass, Neville Ave, 21 Feb 2023 (photo by Kate St. John)

On Pitt’s campus Cornelian cherry trees (Cornus mas) produced yellow flowers.

Flowers of Cornelian Cherry, 20 Feb 2023 (photo by Kate St. John)

Red maples (Acer rubrum) bloomed next to Carnegie Museum …

Red maple flowers near Carnegie Museum, 20 Feb 2023 (photo by Kate St. John)

… and at Frick Park the maple branches looked thick with tiny flowers, including yellowish pollen-bearing ones.

Maple trees against a blue sky. Branches look thick with small flowers and pollen anthers, Frick Park, 23 Feb 2023 (photo by Kate St. John)

This week, tiny leaves opened on jetbead (Rhodotypos scandens) and a few honeysuckle bushes. Unfortunately invasive plants are first to leaf out.

New leaves opening on jetbead, Frick Park, 23 Feb 2023 (photo by Kate St. John)

The coming week will be like a wet blanket: above freezing, gusty wind, lots of rain.

(photos by Kate St. John)

Signs of an Early Spring

Daffodil buds swelling, 13 Feb 2023 (photo by Kate St. John)

18 February 2023

Since a low temperature of 6°F two weeks ago, this month’s weather barely dipped below freezing (until this morning) and twice reached more than 70°F. This week I found signs of an early spring, some of which will survive today’s low of 22°F.

The swelling buds of daffodils, above, and tulip leaves, below, were evident six days ago. Both will probably survive today’s frost.

Tulip and lily leaves spring up, 12 Feb 2023 (photo by Kate St. John)

Yesterday I found early flowers that won’t fare so well.

  • A few early blossoms of Cornelian cherry (Cornus mas)
Cornelian cherry in bloom, 17 Feb 2023 (photo by Kate St. John)
Red maple flowers blooming, 17 February 2023 (photo by Kate St. John)

The swollen red maple buds are armored against frost if they’re not open too far.

Red maple buds swollen, 17 Feb 2023 (photo by Kate St. John)

Unopened American elm (Ulmus americana) buds are in good shape to wait out the cold.

Elm buds swelling, 17 Feb 2023 (photo by Kate St. John)

These early signs are two weeks ahead of the earliest spring I’ve ever recorded. The spring of 2012 was so hot that all of April’s wildflowers bloomed in March.

Will we have a spring like that this year? Or is this just the temporary hot-cold yo-yo of climate change?

p.s. I also found piles of fluff from London plane trees (click here to see what that looks like).

(photos by Kate St. John)

Seen This Week

Sunrise, 11 Jan 2023 (photo by Kate St. John)

14 January 2023

The sunrise was gorgeous and cold last Wednesday when a group of us decided to walk at Jennings in Butler County. We saw few birds but there were ice heaves, buttress roots on an elm, and the seeds of old man’s beard (Clematis drummondii).

Ice heave at Jennings, Butler County 11 Jan 2023 (photo by Kate St. John)
Elm tree with buttress roots, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)

When old man’s beard is in bloom it’s called virgin’s bower, transforming it from a young woman to an old man in a matter of months.

Seeds of Virgin’s bower, a.k.a. Old man’s beard, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)

My friends who live north of the city have not seen many dark-eyed juncos at their feeders this winter, but juncos are definitely present at the Frick Park Environmental Education Center. Charity Kheshgi posted photos of our recent trip to Frick.

(bird photos by Charity Kheshgi embedded from Instagram, all other photos by Kate St. John)