Yearly Archives: 2012

Pokeweed In Stages

Plants & Fungi
Pokeweed (photo by Kate St. John)

16 August 2012

August is prime time for observing pokeweed (Phytolacca americana), a tall perennial that’s easy to find in waste places and along roadsides.  Though its name is “weed,” I love its colors.

In winter pokeweed dies back to the taproot but by August it’s 6-10 feet tall with spreading branches.  The succulent stems are stout and reddish with deep green alternate leaves up to 16″ long.  This plant is big.

Pokeweed’s flowers bloom on racemes that curl up while flowering and droop down when heavy with fruit.  This month you can see the flowers and fruits in all stages of development, often on the same raceme.

Here the flowers show five white petal-like sepals and nascent green berries in their centers.  Notice how the stem is pink.  Pink, white, green.

Pokeweed flowers from bud to incipient fruit (photo by Kate St. John)

After the flowers are pollinated the green berries grow larger. On this stem the berries are all the same age, but that’s pretty rare.

Unripe pokeweed fruits (photo by Kate St. John)

More often the berries range from unripe green to ripe blue-black on the same stem.  This raceme shows nearly every stage in the berry life cycle.

Mix of unripe and ripe pokeweed fruits (photo by Kate St. John)

Ripe pokeberries are a favorite food for catbirds and cardinals, robins and mockingbirds, thrashers and waxwings. When the berries are gone the empty stem puts on a final show in gorgeous magenta.

Pokeweed stem after the fruit has been eaten (photo by Kate St. John)

Like many plants pokeweed is toxic though if properly prepared the young shoots can be eaten in Spring.  The song about eating pokeweed, Poke Salad Annie by Tony Joe White, might lead you to believe lots of people eat it.

Don’t attempt to eat pokeweed until you know how to prepare by it! Everything you need to know is in this video from Edible Mountain on West Virginia Public Broadcasting:

On the plus side, the deep purple berry juice makes a beautiful red dye.

Pokeweed’s colors are a delight at every stage.

(photos by Kate St. John)

Where Not To Play Outdoors

Weather & Sky

NASA satellites have uncovered fascinating things about our world.  One of them is shown on the spinning colored globe above.

This 15-second video is a composite map of lightning flashes observed by NASA OTD and LIS instruments from April 1995 through February 2003. Places with virtually no lightning are white, low levels are purple, then increasing amounts pass through the colors of the rainbow finally to red, black and white again.

Let’s slow it down and look more closely. Here’s NASA’s static map of the same thing showing the distribution of lightning per square kilometer per year.

It’s interesting to note the hot and cold spots:

  • Lightning is far less frequent over water than land.
  • It virtually never occurs at the poles.
  • Winter is a great lightning suppressor.  I can count on one hand the number of times I’ve seen lightning while it’s snowing.  Those times were quite memorable.
  • The worst place for lightning in the U.S. is Florida.
  • Be careful in Singapore, northern Columbia, and Kashmir.
  • There’s so much lightning in equatorial Africa that the map-maker ran out of colors!

Clearly it’s unsafe to play outdoors in the DR Congo.  It’s hard to imagine how people cope with it there.

 

(lightning map from Goddard Space Center lightning study, 2003.  Spinning globe created from NASA lightning map and posted on YouTube by “scienceonasphere.”)

 

p.s. We had some sneaky lightning yesterday afternoon. A downpour, then the rain stopped and while everything was dripping… BAM! It sounded like an explosion. I’m glad I was indoors.

Made In The Shade

Beyond Bounds, Musings & News
Coffee plantation in Brazil (photo from Wikimedia Commons)

Here’s a photograph of a coffee plantation in the mountains of Brazil.

What’s wrong with this picture?

The trees are missing.  And so are the birds.

Last week the University of Utah announced the results of a new study on bird diversity that compared intact tropical forest, agroforests, and open farmland.  The result was not surprising:  Birds do better in agroforests than on farms.

Agroforests are “a type of farm where the crops are grown under trees at a reasonable density,” according to study author Çagan Sekercioglu. “Often, it’s not like forest-forest — it feels more like a open park.”

In the past, coffee and chocolate crops were both grown in agroforests — or in full tropical forest — because they are shade-loving plants.

But agri-business found even moderately shady habitat too labor intensive.  Always on the lookout for ways to cut costs, they bred coffee bushes to tolerate full sun.  For the past two decades they have cleared land, planted coffee in the sun, and harvested it mechanically.

Sadly, bird diversity drops as the habitat becomes more open. The study analyzed over 6,000 species and found that the more open the land, the fewer insect-eaters (flycatchers and warblers), fruit eaters (orioles and parrots), and nectar-eaters (hummingbirds).  Agroforests can support many of these species but the study showed that open farmland supports only seed and grain eaters — and these birds are often considered pests.

Does open farmland south of the border affect “our” birds?

Yes.  Most of our breeding forest birds are neotropical migrants who spend less than half their lives in North America.  The majority of their time is spent in tropical forests — or agroforests — in Central and South America.

Every year there are fewer intact forests and fewer agroforests.  Meanwhile many of our neotropical migrants are in decline including cerulean warblers and scarlet tanagers.

You can help. Your coffee is good for birds if it’s made in the shade.

How do you know if coffee is shade-grown?

Check the label for bird-friendly, shade-grown certification by a trustworthy environmental organization such as the Smithsonian Migratory Bird Center (SMBC) or the Rainforest Alliance. (Unfortunately some manufacturers have co-opted the term shade-grown because they know it’s worth more.)

Certified bird-friendly coffee and chocolate(!) aren’t always easy to find.  If you have a favorite place to buy them, let us know by leaving a comment.

(photo by Fernando Rebêlo from Wikimedia Commons.  Click on the caption to see the original)

Click here for more on the University of Utah bird study.

Assassins In Their Midst

Insects

These flowers look beautiful and innocent, visited by butterflies and bees, but there are assassins in their midst.

I should have known there would be predatory insects in this setting but I was surprised to learn about assassin bugs.

There are over 4,000 species of them, all characterized by a short 3-segmented curved beak that lies in a groove between their raptorial front legs.  They eat by sucking liquids.  The beak is their killing tool.  Their victims are insects, caterpillars and bees.

After grabbing his victim with his front legs an assassin bug brings his beak forward, stabs his victim, and injects enzyme-filled saliva that paralyzes the victim and liquifies his insides.  The assassin bug then sucks the liquified innards out of his prey.

Ewww.

You can see the deadly beak curled under the head of the assassin bug pictured below.  There are graphic photos of these bugs eating insects, but I’ll spare you.

 

Most assassin bugs are active hunters on trees, bushes and weeds but one group, aptly named ambush bugs, lies in wait on flowers.  They’re camouflaged by yellow, orange or red body parts so their victims can’t see them.  Then they pounce.

This ambush bug matches the black-eyed susan and wears pollen as a disguise. He even appears to be smiling for the camera.  Don’t be fooled.

 

Fortunately the vast majority of assassin bugs are uninterested in mammals and won’t bite humans unless mishandled.

I shouldn’t be surprised by that either.   Never mishandle an assassin.

 

(photo credits: flowers by Kate St. John.
Assassin bug (UGA1435167) by Clemson University, USDA Cooperative Extension, Bugwood.org
Ambush bug (UGA2106054) by David Cappaert, Michigan State University, Bugwood.org)

Evening Primrose

Plants & Fungi

Blooming now in Pennsylvania, the evening primrose fully opens at twilight.  Similar species called sundrops are open during the day.

Both flowers are in the Oenothera genus and are masters at opening and closing in response to light.  It takes these flowers only a minute to do it.   Click here to watch one opening.

Evening primroses are hardy and widespread, in fields and along roadsides.  Dianne Machesney found this one at Scotia Barrens.

(photo by Dianne Machesney)

p.s. Monday August 13: It’s cloudy and gray this morning. Evening primroses are open in Schenley Park.

Haws

Schenley Park, Trees

This week I found a bumper crop of haws littering the sidewalks in Schenley Park.

Haws are the fruit of hawthorn trees:  short trees with low branches, tangled twigs and long, thin, leafless thorns (1″-2″ long).  The thorns are a great clue for identifying the tree.  Haw+thorn.

Hawthorn fruits look like small apples or rose hips, all members of the rose family.  They’re a favorite food of robins and cedar waxwings, and people sometimes preserve or ferment them into jam, jelly, snacks and beverages.  The trees occur worldwide in the northern hemisphere so there are many recipes.

Hawthorn trees are really easy to identify as a genus (Crataegus) but difficult as a species because they hybridize and speciate so often.  At one point botanists listed more than 1,100 species in North America but they’ve since clumped them down to about 100.

The Sibley Guide to Trees says hawthorn species are so similar that identifying them is best left to experts.  However, armed with rudimentary knowledge and my Sibley guide, I’ll go out on a limb for these Schenley trees.

My guess is that they’re a variant of Downy Hawthorn (Crataegus mollis) because the haws are ripening in August and the ripe ones soon fall to the ground.

(photo by Kate St. John)

Taking A Dip

Bird Behavior, Birds of Prey, Schenley Park

  • Immature Red-tailed Hawk, bathing at Schenley Park, August 2012 (by Gregg Diskin)

We’ve all seen robins splashing in water but how many of us have seen a hawk take a bath?

Last Saturday it was already hot when Gregg Diskin took a walk through Schenley Park with his camera.  Near Bartlett Playground he saw a hawk disappear under the bridge so he walked down the path to investigate.  There he found an immature red-tailed hawk taking a dip in the stream.

Bathing is a relatively vulnerable activity so we rarely see adult hawks doing it.  My hunch is that this bird was one of the two immature red-tails who starred in Monday’s blog.  He had almost no fear of people, felt right at home, and continued to bathe while Gregg snapped a series of pictures.

Click on the photo above for a slideshow of the red-tail’s bath.  At the end he has something to say to Gregg.

(photos by Gregg Diskin)

Gotta Fishy! Gotta Fishy!

Bird Behavior, Water and Shore

Last weekend we spent four days at Cape Cod where I had the opportunity to see piping plovers and least terns, two birds that are extremely rare in southwestern Pennsylvania.

Both species are endangered because they nest on the ground on sandy beaches, the same places where humans like to own property and spend their vacations.  At the Cape, nesting areas are roped off above the water line and dogs are prohibited off leash (or prohibited altogether).

During our stay people and birds coexisted peacefully.  Some people, like me, were fascinated by the birds.

At Ridgevale Beach the least terns were numerous and vocal at low tide.  Several immature terns were still being fed by their parents even though they could fly.  The youngsters waited on the sand, immobile and camouflaged, while mom and dad hunted for food.

Their parents flew over the water looking for finger-length silver fishes.  Sometimes they hovered above, waiting for the perfect moment to dive and snag a fish.

Zip!  As soon as a tern plucked a fish out of the waves he flew around the area giving a loud, continuous, 4-note call, “Gotta fishy! Gotta fishy!  Gotta fishy!”

Eventually he flew back to land with a flourish of upraised wings and present the fish to his youngster.  Sometimes the youngster just blinked and looked away.  He wasn’t hungry!   The fish were that plentiful last weekend.

When the colony found a big school of fish they were all in the air, flying swiftly, carrying fish, calling “Gotta fishy, gotta fishy, gotta fishy.”

Their voices carried so far that I often heard least terns before I reached the beach.

(photo by Steve Gosser)

The Prevailing Wind

Weather & Sky
Wind-shaped trees in Wales (photo from Wikimedia Commons)

8 August 2012

Except during storms, Pittsburgh is not a very windy place.  This is especially true in July and August when our average wind speed drops to 9 mph and is usually from the west.

The direction of the “usual” wind is called the prevailing wind and it shapes our weather, rainfall, landscape and vegetation.

In places where the wind is strong the prevailing wind can be seen even when it isn’t blowing.  Witness the trees in the photo above at Cardigan Bay in Wales.

On a global basis the prevailing wind is influenced by the earth’s rotation.  As the earth spins the atmosphere swirls in a consistent way:

  • From the equator (0o) to latitude 30o north and 30o south the prevailing winds are from the east.  These are the trade winds that brought Christopher Columbus and cattle egrets(*) to the New World.
  • From latitudes 30o to 60o the prevailing wind is from the west.  The westerlies returned the trading ships to Europe.
  • From latitudes 60o to the poles the prevailing wind is again from the east.

At any given point on earth the prevailing wind might not obey these rules due to location at a border latitude (30o, 60o), topography, or seasonal change.

Pittsburgh, at 40oNorth, has no stark topography so our prevailing wind obeys the general rule:  it’s from the west or WSW.

We can see this on a wind rose that plots wind direction over time. Each data point is placed at its compass position.  The more data points from that position, the longer the ray from the center.

Here’s a Pittsburgh wind rose from EPA showing our daytime wind for the seven months of ozone season (April 1 to October 31).

Windrose for Pittsburgh, PA during Ozone season, April-to-October (image from EPA)

Click here to see a wind rose depicting 30 years of data on Pittsburgh’s wind direction and here for the wind roses of 11 secondary airports (smaller towns) in Pennsylvania.

And what’s the wind like for those trees in the photo above?  Right now it looks like this (scroll down to see the label “Cardigan Golf Club” and watch the wind swirl around the UK).

* Cattle egrets are originally from Africa.  They flew to South American on their own — perhaps in a strong storm carried by the prevailing winds — the trade winds.

(photo of wind-shaped trees by Rudi Winter from Wikimedia Commons. Wind rose from epa.gov. Click on the captions to see the originals.)

Potato Chip

Bird Behavior, Songbirds

Have you seen a female goldfinch lately?

Female goldfinches disappear during most of July to spend 95% of their time on the nest.  They don’t even stop incubating to eat.  Their mates feed them at the nest by regurgitation.

To do this the male goldfinch (above) stores seeds in his crop, then flies in a big, undulating circle above his nesting territory, all the while singing “Potato chip, Potato chip.”

If his lady is hungry she calls softly to him from the nest, “teeteeteeteeteetee” and he flies down to feed her.

After the eggs hatch, the female broods them for four days.  And then, at last, she’s off the nest to help her mate feed the babies. Soon the fledglings will be at the feeders, too.

If you heard the “Potato chip” song above your yard in July, watch for goldfinch fledglings in August.

(photo by Chuck Tague)