Category Archives: Phenology

Now Blooming

Phenology, Plants & Fungi, Schenley Park
Hepatica at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

7 April 2019

What’s blooming in southwestern Pennsylvania this weekend?

Yesterday’s joint outing of the Botanical Society of Western PA and Wissahickon Nature Club found a lot of spring flowers at Cedar Creek Park in Westmoreland County, 6 April 2019.

Hepatica was blooming in shades of white, pink and blue. In the photo above, the leaves aren’t visible so I can’t tell if this plant is round-lobed (Anemone americana) or sharp-lobed (Anemone acutiloba) hepatica.

Harbinger of Spring (Erigenia bulbosa) was blooming along the valley trail. Did you know this plant is in the Carrot family?

Harbinger of spring at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Snow trillium (Trillium nivale) covered the hillside beyond the last bridge …

Snow trillium at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

… and spicebush’s (Lindera benzoin) tiny yellow flowers were a nice surprise.

Spicebush at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Most of the spring beauty was not in bloom but we found Carolina spring beauty (Claytonia caroliniana), a specialty at Cedar Creek shown below.

Spring Beauty at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

This bloodroot (Sanguinaria canadensis) was bright white by the bike trail. Its leaves are barely visible, clutching the stem, while a garlic mustard leaf tries to photo-bomb the bottom corner.

Bloodroot at Cedar Creek Park, 6 April 2019 (photo by Kate St. John)

Meanwhile, how are the buckeye buds doing in Schenley Park? Some were unfurling on Friday 5 April 2019. Note the CORRECTION ABOUT BUCKEYES below!

Yellow buckeye buds, starting to unfurl their leaves in Schenley Park, 5 April 2019 (photo by Kate St. John)

CORRECTION ABOUT BUCKEYES: Last week Stephen Tirone investigated the buckeye buds in Schenley and Frick Parks and learned that these are yellow buckeyes (Aesculus flava) not Ohio buckeyes (Aesculus glabra). Though Ohio buckeyes are more common in the wild, Pittsburgh’s parks are not “wild.” Schenley and Frick Parks were landscaped with ornamentals when the parks were established more than 100 years ago. Yellow buckeyes are often planted as ornamental trees and may be hybridized to produce showy flowers. So, yes, these are yellow buckeyes.

(photos by Kate St. John)

Pennsylvania Fire Season

Phenology, Weather & Sky
Fire in the Wayne National Forest, March 2009 (photo from Wikimedia Commons)

4 April 2019

Spring is fire season in Pennsylvania. 85% of our wildfires occur in March, April and May.

There’s no drought in Pennsylvania right now, nor in most of the U.S. — as shown on the map below.

US Drought Monitor for 28 March 2019

But you don’t need drought to have a fire. All you need are dry conditions, fuel, and a spark. In Pennsylvania we have all three in the spring: low humidity, gusty winds, and lots of old leaf litter drying out in the sun. The spark comes from people.

98% of Pennsylvania’s wildfires are caused by people and most of those are caused by people burning debris. On a sunny windy day those fires blow onto dry grass and escape to the wild. In April 2016 more than 10,000 acres burned in Pennsylvania.

Yesterday the fire danger was high in our state because the weather was so nice — warm and sunny with gusty winds. Across Pennsylvania people were out doing yard work. Some were probably burning piles of debris. I haven’t heard if there were any fires. (The fire danger is lower today, 4 April 2019, because the weather changed.)

U.S. Forest Service Wildfire Danger Forecast

If you live in a place that allows outdoor trash burning be careful out there! Spring is Pennsylvania fire season.

(photo of fire from Wikimedia Commons (actually a prescribed burn). Maps from US Drought Monitor and U.S. Forest Service Wildfire Danger Forecast; Click on the captions to see the originals)

Note: Allegheny County does not allow outdoor trash burning.

Buds About To Burst

Phenology, Schenley Park, Trees
Yellow buckeye buds about to burst, 1 April 2019 (photo by Kate St. John)

Yesterday I found these buds about to burst in Schenley Park.

Yellow buckeyes (Aesculus flava) are one of the first trees to leaf out in the spring, unfurling their dramatic palmate leaves. They’re such a welcome splash of green that I photograph them nearly every year. This is the first time I noticed the bud at this stage. I didn’t expect it to be red.

Over the years my buckeye photographs have documented the vagaries of spring in Schenley Park. In cooler years — such as 2015 — the buds weren’t this far along in mid-April. Here’s a closed bud on 15 April 2015.

Closed bud on 15 April 2015 (photo by Kate St. John)

In hot years — such as 2012 — the buds opened weeks ahead of schedule. This buckeye was completely leafed on 19 March 2012.

Yellow buckeye tree 19 March 2012 (photo by Kate St. John)

This year appears to be a “normal” spring … whatever that means these days.

(photos by Kate St. John)

Late March in Schenley Park

Phenology, Plants & Fungi, Schenley Park
  • Cornelian cherry (Cornus mas), 28 March 2019 (photo by Kate St. John)

Spring is coming at a good pace this year. Unlike hot years, such as March 2012, there’s time to appreciate each new leaf and flower before the next set appears.

My photos above show a selection of leaves and flowers at Schenley Park this past week. Most were taken on March 28 but the real surprise was coltsfoot blooming on St. Patrick’s Day. That flower hid for ten days and appeared again last week.

Unfortunately, all of these plants are alien and some are invasive. Their ability to spring ahead of the local plants gives them an advantage all year long.

Click here for that same honeysuckle branch, bud-to-leaves on March 11, 16.

(photos by Kate St. John)

The Trees Are Snowing

Phenology, Trees, Winter Weeds & Trees
Drift of fluffy seeds from London plane trees, 17 March 2019 (photo by Kate St. John)

28 March 2019

Last week I found fluffy drifts on the sidewalks in my neighborhood. They’re the airborne seeds of London plane trees (Platanus × acerifolia), planted in Pittsburgh in the late 1800s because they’re tolerant of air pollution.

Like their parents — oriental plane tree (Platanus orientalis) + American sycamore (Platanus occidentalis) — London plane trees retain their dangling seed balls over the winter.

London plane tree fruit in autumn (photo from Wikimedia Commons)

Then in the first warmth and light of spring the seed balls disintegrate and the seeds blow away. You’ll find drifts near American sycamores, too.

London plane tree fruit disintegrating (photo from Wikimedia Commons)

In March the trees are snowing.

(seed drift photo by Kate St. John; remaining photos from Wikimedia Commons, click on the images to see the original)

Weeping Willows Hint of Spring

Phenology, Schenley Park, Trees
Weeping willow turning yellow, Schenley Park, 15 Feb 2019 (photo by Kate St. John)

Weeping willows (Salix babylonica) are popular landscape trees that were brought here from Asia. They’re easy to notice at this time of year because their drooping stems turn yellow in very early spring. From a distance you see a splash of yellow.

Imported species, especially those from Europe, grew up in a steady climate with few spring surprises so they’re quick to bloom in the spring and late to drop their leaves in autumn.

Meanwhile our native trees are still brown, conservative about producing tender shoots because they know that volatile spring weather can bring a killing frost in April.

Are you tired of winter? Watch for the weeping willow’s hint of spring.

(photo by Kate St. John)

Watch for Witch Hazel

Insects, Phenology, Trees
Witch hazel flowers catch the light after the leaves are gone, November (photo by Kate St. John)

When the leaves are gone these lacy flowers stand out in the forest.

American witch hazel (Hamamelis virginiana) blooms from late October into December in eastern North America.  Its delicate yellow flowers smell like lemon.

Witch hazel flower, October in Schenley Park (photo by Kate St. John)

Since witch hazel blooms when few insects are out how are the flowers pollinated?

In 1987 Bernd Heinrich found that owlet moths come out at night to sip the flowers and thereby pollinate them.

The moths survive cold weather by hiding under leaf litter during the day, then shivering to warm up and fly at night. Click here to learn more.

(photos by Kate St. John)

When Will Most Of The Trees Be Bare?

Phenology, Schenley Park, Trees
Leafless bur oak, Schenley Park, 4 Nov 2011 (photo by Kate St. John)

Every year I record the date when most of the trees are bare on my favorite hillside in Schenley Park — the hill at the end of the Greenfield Bridge.

In 2008 the leaves were gone by 2 November.  In 2012 Hurricane Sandy stripped them from the trees by 4 November.

Last year the changes happened much later. In 2017, the leaves were still green in late October and more than half were still on the trees on 27 November.  Here’s a 2017 slideshow of autumn trees on that hillside.

  • 26 October 2017: Lots of green at the end of October 2017.

This year is similar to last so I wonder … When will most of the trees be bare?  November 15?  20?  30? Later?

Let me know how the trees look where you live and vote for the date “When Most of the Trees Will Be Bare” by leaving a comment below.

HINT!  Two factors that affect leaf loss on this hillside:  (1) More than half of the trees are oaks; oaks drop their leaves later than maples.  (2) This city location is warmer than surrounding counties.

(photo by Kate St. John)