Archive for the 'Schenley Park' Category

Oct 05 2013


Published by under Plants,Schenley Park

Beggar Ticks (photo by Kate St. John)

Related to Spanish needles, most of the Beggar Ticks (Bidens frondosa) in Schenley Park have not yet gone to seed.

When they do they will stick tight to my clothing.  It happens every year.

Click here to see the seeds.

(photo by Kate St. John)

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Oct 03 2013

Acorns Are Connected

Acorns of northern red oak (photo from Wikimedia Commons)

Stop and listen in Schenley Park right now and you’ll hear acorns falling, blue jays calling and squirrels scurrying.   It looks like a bumper crop for acorns in Pittsburgh. (*see p.s.)

Right now the red oaks are putting on a show.  Acorns in the white oak group mature in the same year they flower.  Acorns in the red oak group take two years to mature so those falling now were formed in the hot spring and summer of 2012, influenced by spring precipitation, summer temperatures and the date of the last killing frost.

Though we (usually*) don’t eat them, acorns are a key link in the woodland food web.  They’re so popular that oaks have evolved an abundance-scarcity strategy to throw off their consumers.  In some years acorns are so abundant that the crop overwhelms the acorn-eaters.  In other years they’re so scarce the consumers go hungry.  To further confuse things the oak groups cycle on different schedules: white oaks have a bumper crop in 4-10 years, red oaks on a 3-4 year basis.

Who eats these acorns?  Squirrels and chipmunks are the obvious consumers but plenty of other species depend on them including white-footed and deer mice, blue jays, red-headed woodpeckers and wild turkeys.  Deer, ruffed grouse, bears, mallards and wood ducks eat acorns, too.

The bumper crops have a ripple effect.  A 24-year study, headed by Clotfelter and Pedersen in the southern Appalachian Mountains of Virginia, followed the effects of acorn crops on rodent abundance, raptor abundance and the nesting success of ground-nesting birds.  They focused on white-footed mice, deer mice and dark-eyed juncoes and found these amazing acorn effects:

  • The population of white-footed and deer mice increases in the year after a bumper crop of acorns.
  • Rodents attract predators so the raptor population increases.
  • Too many rodents and raptors causes junco nest failure due to predation on eggs, nestlings and birds.
  • Mice eat gypsy moths so the gypsy moth population drops.
  • The number of ticks increases as white-footed mice and deer increase.

And then, this information from PLOS links acorns to Lyme disease:  Lyme disease increases predictably two years after an acorn bumper crop because white-footed mice are a main reservoir for the Borrelia burgdorferi bacteria.

Don’t blame the acorns.

Everything is connected to everything else.


(photo from Wikimedia Commons. Click on the image to see the original)

*p.s. Is this a bumper crop year?  I wrote about acorns because I’ve been dodging them in Schenley Park as they fall, but not all the trees are prolific.  Hmm….

*”We don’t usually eat acorns”:   Well, we can … after a lot of work.  See kc’s comment!

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Aug 22 2013

Now Blooming: White Wood Aster

Published by under Plants,Schenley Park

White wood aster in Schenley Park (photo by Kate St. John)

If you wait long enough mysteries reveal themselves.

In April 2012 I displayed this photo of squawroot and asked readers the identity of the green leaf on the left side of the picture.  I thought it might be an invasive species.

Squawroot in Schenley Park, 2 April 2012 (photo by Kate St. John)

Mark Bowers and Loree Speedy answered it was probably White wood aster (Eurybia divaricata) which grows in large patches and therefore might look invasive, though it’s not.

Last week I finally put the lonely leaf and its flower together when I found the asters blooming in the same place where the leaves appear in the spring.

And yes it was in patches, small and large.  Small above, large below, in Schenley Park.

Patch of White wood aster in Schenley Park (photo by Kate St. John)

Mystery solved.   …Unless I was fooled again.


(photos by Kate St. John)

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Aug 20 2013

Are My Ears Ringing?

iBroad-winged tree cricket, Oecanthus latipennis (phoito from Wikimedia Commons)

This month as I enter Schenley Park and walk up tree-lined Greenfield Road I begin to worry.  With the sound of the expressway on my left and street traffic on my right my ears are overloaded with an additional high-pitched noise.   Are my ears ringing?

I experiment by looking up while listening.  It’s worse.  I plug my ears.  It’s a little better.  The sound of traffic makes it hard to pick out.  What is that high-pitched whirring sound?

August is bug season so I’ve come to the conclusion that the sound is tree crickets, probably one of these (click here).  Maybe the Four-spotted tree cricket (Oecanthus quadripunctatus) who sings day and night and is common along roadsides.

To give you an idea of what I’m hearing, click here for the four-spotted tree cricket and a video with his song.  (The video repeats with a pause at the end.  The sound on Greenfield Road never pauses, there are so many.)

I would try to find these insects but all the online sources say they’re very hard to see — and that’s coming from the experts!  So I’m accepting this as the song of tree crickets and resting assured that my hearing is not in danger.

For more information on tree crickets I recommend this website: Tree Crickets Sweet Sounds of Summer by Nancy Collins at where you can find close-up photos, songs and videos.


p.s.  In settings with less background noise I’ve noticed the tree crickets are in full force this week.

(photo of a broad-winged tree cricket (NOT a four-spotted tree cricket) from Wikimedia Commons.  Click on the image to see the original)

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Aug 08 2013

Experiments with Jewelweed

Published by under Plants,Schenley Park

Jewelweed jewels (photo by Kate St. John)

Tuesday dawned cool and clear with patchy morning fog and lots of dew.  As I walked to work through Schenley Park I noticed that the jewelweed leaves were dripping with tiny round jewels.

Jewelweed gets its name from the way water beads up on top of the leaves but I’d never before seen jewels drip from the tips so I took a picture.  Then I experimented.

What would happen if I touched a jewel?

It came off on my finger and stayed in its rounded jewel form.  It wasn’t pure water.  It didn’t roll off.
Jewel on my fingertip (photo by Kate St. John)


While I was experimenting with these tiny drops Art Schiavo, an avid birder from Hershey, PA, was thinking about jewelweed too (amazing coincidence!) and sent me this message:

“I’m sure you know that jewelweed is in the Impatiens Genus.  I’m also fairly certain you know that its medicinal value is insect bite, stinging nettle exposure, and poison ivy relief, but did you know that the seeds are edible and taste similar to sunflower seeds?”

Wow.  I had no idea you could eat the seeds.  A little investigation uncovered this document that explains which parts of the plant are edible and how to cook them.  There’s no need to cook the seeds but good luck catching them when the casing pops.

More experiments ahead!


(photos by Kate St. John)

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Jul 30 2013

Oak Wilt Strikes Again

Published by under Schenley Park,Trees

Oak wilt in Schenley Park, 5 July 2013 (photo by Kate St. John)

I love trees so much that I jump at the chance to learn more about them.

Back in February 2011 I learned about the threats facing 60% of our city park trees when the Pittsburgh Parks Conservancy presented a public event called Preserving Pittsburgh’s Trees: Action and Recovery.   I was already familiar with emerald ash borer since I first saw it in Schenley in May 2010 but I learned about something I’d never seen before: oak wilt.

While Schenley Park had been coping with the death of all its ash trees, the other three big parks — Frick, Highland and Riverview — had experienced oak wilt as well.

Oak wilt is caused by a fungus that doesn’t spread easily but can kill a tree in 30 days.  The fungus travels in the oak’s vascular system and when the tree detects it it blocks those vessels.  The blockage kills the tree. It’s the arboreal equivalent of a stroke.  Watch the 13 minute video here to see how this happens.

After the conference I began to watch Schenley’s oaks with new interest.  Two years passed.  Early this month I could tell something wasn’t right at Prospect Circle.  I emailed this and other photos to Phil Gruszka, Director of Park Management and Maintenance at the Pittsburgh Parks Conservancy, and he confirmed that oak wilt had struck again.  He also started the ball rolling to eradicate it.

Fortunately the fungus spreads slowly and that’s the key to stopping it.  It’s either carried into an open wound by sap-eating beetles (this is harder than you think) or it travels from oak to oak via root grafts.  Amazingly, the roots of adjacent oaks graft to each other when they touch underground.  In a pure oak stand they become one huge vascular system.

There is no cure but future deaths can be prevented by cutting down the affected trees, trenching the perimeter to prevent uninfected roots from entering the danger zone, and medically treating the oaks just outside the perimeter.

In the not too distant future a large patch of dead and dying oaks will be chopped down at Prospect Circle.  This will look ugly at first but will save all the other beautiful oaks along the road and hillside.

For more information about oak wilt, read these Pittsburgh Parks Conservancy blogs about the episode in our parks in 2010:


(photo of the oak wilt trees in Schenley Park, July 2013, by Kate St. John)


p.s. Learn more about the trees in our city parks at this link on the Pittsburgh Parks Conservancy website.

UPDATE on 18 October 2013 from the Pittsburgh Parks Conservancy –> click here.

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Jul 17 2013

Metallic Green On…

Metallic green bee on Spotted knapweed (photo by Kate St. John)

Close looks reveal new wonders.

Until recently I had no idea that metallic green bees existed.  Then I saw one on a chicory flower in Schenley Park and that started the ball rolling.

Soon I found another one, this time on spotted knapweed on the Montour Run bike trail.  She’s a beautiful green color with huge yellow pollen sacks on her legs.  (I don’t know the sex of this bug; just guessing.)

My searches on the web indicate she’s one of 11 species of Agapostemon sweat bees, bugs of the western hemisphere.  If I had known what to look for I could have used this guide at Discover Life to identify her species.

Though sweat bees are sometimes attracted to sweat, the bees I found were only interested in flowers, especially blue and violet flowers like spotted knapweed.

Spotted knapweed (Centaurea maculosa) has a pretty flower but it’s an invasive species that’s consumed 7 million acres of North America.  It gains a foothold in disturbed soil, then spreads through high seed production, toxins in its roots that inhibit other plants, and an unpalatable taste that prevents deer and other animals from eating it (alas!).

It’s identified by its distinctive thistle-like flower head with black-fringed bracts.

Spotted Knapweed (photo by Kate St. John)

Spotted knapweed is blooming everywhere right now.

Look closely and you might find a native metallic green bee taking a sip.


p.s. Check the comments for a link to a cool close-up by Mike Vosburg!

(photos by Kate St. John)

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Jul 13 2013

Enchanters’ Nightshade

Published by under Plants,Schenley Park

Enchanters' Nightshade in Schenley Park (photo by Kate St. John)

This plant has a conspicuous name and inconspicuous flowers.

Enchanters’ Nightshade (Circaea lutetiana, ssp. canadensis) blooms in shady woodlands in June and July. Subspecies are native to Europe, north Africa, western Asia and eastern North America.

The plant’s common and scientific names both refer to magic though it’s hard to find out why.  Some sources say Circe used this plant to turn Odysseus’ men into swine, thus the genus name Circaea.  The species name lutetiana is the Latin name for Paris.  Is this Paris the city?  Or is it Paris of Troy who started the Trojan War that spawned Odysseus’ epic journey home?  The sources don’t agree.

I like this plant’s open airy structure but that makes it hard to photograph.  I spent a lot of time on my knees in Schenley Park and threw away a lot of bad pictures.  Above is the best I could do.

To see the flowers, here’s a closeup from Wikimedia Commons taken by Randy Nonenmacher in Skaneateles, New York.

Close-up of Enchanters' Nightshade flowers (photo by Randy Nonenmacher on Wikimedia Commons)

Notice how the flower stems turn down and the receptacles(*)  are poised to become the seed pods. The flowers look so delicate.



(whole-plant photo by Kate St. John.  Close-up from Wikimedia Commons; click on the close-up to see the original image)

(*) Receptacles are defined in this diagram of a flower.

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Jul 11 2013

Attack of the Aphid Lions

Since I wrote about red aphids I’ve been back to Schenley Park looking for their predators.

I knew I might find aphid lions (lacewing larvae) but I didn’t notice them on the plants until I saw this amazing video.  That’s because aphid lions wear disguises!

Watch the video and see why they’re incognito.

So much goes on in the tiny world of insects that we never notice.

(video from the Terra Explorer Project on YouTube)

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Jul 09 2013

The Bane Of Fleas

Published by under Plants,Schenley Park

Fleabane (photo by Kate St. John)

Here’s a flower so common you might think it’s a weed.

Fleabane is native to North America and very common in western Pennsylvania.  It grows so easily that you’ll find it along roadsides.

Pictured here is daisy fleabane (Erigeron annuus) in Schenley Park.  Its white or pink-tinged flowers are 0.5 to 0.75 inches wide and its leaves do not clasp the stem.  Common or Philadelphia fleabane (Erigeron philadelphicus) has slightly larger, pinker flowers and its leaves *do* clasp the stem.  To remember this think “Common = Clasp.”

Fleabane flowers respond to light.  The white rays open and close at sunrise and sunset. Before they bloom they bow their heads.  In the morning fleabane pulls up its flower heads and opens its white rays.  This seems like a lot of exercise for a small flower but I imagine it’s meant to prevent nighttime pollination.

Fleabane got its name from the belief that the dried plant kills fleas.  Bane comes from an Anglo-Saxon word meaning murderer or destroyer and is often used in plant names.  For instance, “baneberry” means death-berry; it’s poisonous.

If wanted to kill fleas I could dry some fleabane.  Thankfully I’ve never had occasion to need it.

(photo by Kate St. John)

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