Category Archives: Winter Weeds & Trees

The Shapes of Trees: Black Locust

Silhouettes of two black locusts in Schenley Park (photo by Kate St. John)

Now that the leaves have fallen we can see the skeletal shapes of trees.  Did you know it’s possible to identify them by shape?

Seven years ago I wrote a series on identifying trees by their buds and bark but I didn’t mention shape except for this gnarly twisted tree, the black locust.

Black locusts (Robinia pseudoacacia) are easy to find in Pittsburgh because we’re within their native range and they grow well in disturbed soil.  They’re often described as brittle and invasive but that’s because of what we did to them. 

Native range of black locust (map from Wikimedia Commons)

Because their hard wood is very durable and prized for furniture, flooring and fence posts, we planted black locusts around the world.  Outside their range the trees became invasive.  Meanwhile their natural enemy, the locust borer (Megacyllene robiniae), followed them wherever they went.

Locust borer larvae drill holes in the heartwood and weaken the tree.  Before 1900 the bugs were in balance but that year the locust borer population exploded everywhere. Since then black locusts are usually infected and brittle so the trees rarely reach full size before they blow down. 

Black locust damaged by locust borer (photo by James Solomon, USDA Forest Service, via Bugwood.org)

But they do retain their distinctive shape.  Here’s another example. 

Gnarled black locust tree (photo by Kate St. John)

On Throw Back Thursday, learn more cool facts about black locusts and how to identify them in this vintage article: Winter Trees: Black Locust.  Then take a walk outdoors to find their distinctive gnarly shapes. 

In the next few months I’ll add more Shapes of Trees as I encounter them outdoors.

(photos by Kate St. John; map from Wikimedia Commons. click on the caption to see the original)

Tiny Opals

Hackberry fruits (photo by Paul Wray, Iowa State University, bugwood.org)

This month I read Lab Girl by Hope Jahren and learned that she made an amazing discovery in 1998 during research for her doctoral dissertation:  Inside common hackberry fruit is a small hard pit with a lattice made of opal.

Hackberry fruits, pictured at top, are drupes similar to cherries and peaches with fleshy fruit surrounding a central pit.  The fruit is thin and the pits are large so we rarely eat hackberries but birds love them.

The pits in cherries and peaches are made of wood (or something like it) but hackberry pits are made of stone: calcium carbonate inside a lattice framework. When Hope Jahren used Xray diffraction on the crushed lattice material its composition came up “opal.” 

When I found this out I searched for the pits under hackberry trees in Schenley Park. At this time of year the fleshy purple fruit is gone, only the white pits remain.  Here’s what I found, one whole, one opened. The exterior is a network of tiny raised lines. 

Opal is in these hackberry pits (photo by Kate St. John)

The pits don’t look like opal and probably never will.  You’d have to use acid to remove the calcium carbonate (the white stuff of seashells) and then examine the remaining latticework under a microscope.  There’s a tiny bit of opal in there.

And so I wonder: How does a tree put opal in its drupes?  I don’t know, but here are the raw materials:

[The rock] Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids, caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed. 

From Opals Down Under

Trees take up water that contains dissolved minerals including the building blocks of opal.

Miraculously, the hackberry tree pulls out what it needs and makes an opal latticework inside its drupes.

Learn how to identify hackberry trees in winter at Winter Trees; Hackberry.  Then search the leaf litter for tiny opals.

For further reading see : Hackberry: A Gem of a Weed

(photo credits: hackberry fruits by Paul Wray, Iowa State University, bugwood.org, hackberry pits by Kate St. John)

Why Not To Clear Your Garden This Fall

Goldenrod gall with a woodpecker hole (photo from Wikimedia Commons)

I’ll bet you have a gardening project planned this weekend or next. Here’s some time-saving advice:  Don’t clear your garden in the fall.

Why not?

  • Seeds on the old plants provide winter food for birds and animals.
  • Insects overwinter on plants in egg masses, cocoons and galls.  Birds eat those insects. 
  • The brush provides shelter for the birds.
  • You won’t have to mulch.
  • You’ll enjoy watching birds among the old plants.

The photo at top shows that an old goldenrod gall contained food for a woodpecker. He hammered a hole to get the bug.

On Throw Back Thursday, read more about this time saving plan in a 2010 article: Why Not to Clear Your Garden

p.s. The only downside I can think of is this: It’s hard to plant bulbs when the old stuff is in the way. 

(photo from Wikimedia Commons; click on the caption to see the original)

Yo-yo

Flowering cherry tree in snow, 4 Jan 2016 at Carnegie Museum in Pittsburgh (photo by Kate St. John)
Flowering cherry tree in snow, 4 January 2016 in Pittsburgh (photo by Kate St. John)

After a month of warm weather, these cherry trees were fooled into blooming in early January at Carnegie Museum.

Then last Monday the temperature dropped into the single digits and hit everything that couldn’t get out of its way.  Nothing could protect those delicate pink flowers.

Unlike plants, birds can get out of the way and some of them decided to leave this week.  In my neighborhood, there were many American robins in December but most of them have left since the cold snap.  Did your robins leave, too?

Meanwhile, don’t be fooled by today’s warmth.  Here’s a graph of Pittsburgh’s actual and predicted morning low temperatures for the first two weeks of January.

Graph of morning low temperatures in Pittsburgh, PA, actual+forecast for January 1-14, 2016 as of 1/9/2016 (graph uses NWS data)
Actual+forecast morning low temperatures in Pittsburgh, PA, January 1-14, 2016 (graph uses National Weather Service data as of 1/9/16)

It’s a yo-yo.

 

(photos by Kate St. John)

From A Different Angle

Bare trees from a new angle (photo by Kate St. John)
Bare trees from a different angle (photo by Kate St. John)

When my camera couldn’t capture this horizontally, I turned it sideways to photograph the trees.

I like them this way better than in the “normal” orientation.

Put your left ear on your left shoulder to see what I mean.

p.s. I took this photo four years ago but didn’t label it.  Based on their bark I think these are sugar maples … but their branches don’t look right.

(photo by Kate St. John)

Listening To The Secret Sounds Of Trees

Woman listening with headphones (photo from Wikimedia Commons)

In early May when the trees leaf out we’ll once again hear the soothing sound of rustling leaves.  Did you know trees make sounds we cannot hear?

Last year an article by Sarah Zhang in Gizmodo caught my attention.  Eavesdropping On The Secret Sounds Of Trees describes the art and science of a Swiss research team who’s recording the internal sounds of trees.

The project, fittingly called trees, attaches sensitive microphones to trunks, branches and even leaves, then records the sounds and analyzes them in light of simultaneous environmental factors such as drought.  Click here and scroll down to hear the clicks, pops, hisses and taps made by a Scots pine (Pinus sylvestris).

Closer to home our trees are getting ready for spring, the sap is running, and it’s maple sugaring time in North America.

Maple sugar bucket hanging on a tree (photo from Wikimedia Commons)

And so I wonder …

If we had those special microphones could we heard the sap rising in the maples?  Or is it so loud that we can hear it by putting our ears to the trees?

I’ll have to see.

 

(photos from Wikimedia Commons. Click on the images to see the originals)

It Was Pretty

Snowy view on 5 March 2015 (photo by John English)
Snowy view on 5 March 2015 (photo by John English)

Yes, last Thursday’s snow was pretty.

It coated the trees like a winter wonderland outside John English’s apartment window (above).

And I found close up beauty in Schenley Park.

Snow in Schenley Park, 5 Mar 2015 (photo by Kate St. John)
One leaf  (photo by Kate St. John)

 

Snow on Queen Anne's lace, 5 March 2015 (photo by Kate St. John)
Queen Anne’s lace (photo by Kate St. John)

 

In December I’d be thrilled by snow but within a few hours I was heartily tired of this beautiful event.

Fortunately it will go away this week.

 

(photo of snowy hillside by John English.  Closeups by Kate St. John)

Mitten Leaves

Sassafras leaves in three shapes and two colors (photo by Kate St. John)

These very different leaves came from the same tree.

Sassafras turns red and yellow in the fall showing off its unlobed leaves, two-lobed “mittens” and three-lobed “paws.”  All three shapes grow on the same tree including both right and left-handed mittens (I checked).

Sassafras (Sassafras albidum) is a medium-sized tree native to eastern North America from southern Maine to Florida to eastern Texas. In Pennsylvania it grows everywhere except on the central high plateau of the Northern Tier.

The tree’s roots, bark, shoots and fruit were used directly in many foods, drinks, perfumes and medicines (think “root beer”) until the essential oil, safrole, was discovered to be carcinogenic and outlawed by the FDA in 1960.  Sassafras by-products can still be used in food and cosmetics as long as they’re certified safrole-free.  Safrole is used in pesticides.

In Europe people plant sassafras as an ornamental for its aromatic scent and unusual leaves.

I found these in the wild in Harrison Hills County Park.

 

(photo by Kate St. John)