HEBERLING LAB

Chestnuts (used to be) on Chestnut Ridge
And across the entire state of Pennsylvania.
 
American chestnut (Castanea dentata) was once a very common tree, native from Maine to Mississippi. In the heart of the Appalachians, the historical range covered the entire state of Pennsylvania. I say “historical” and “was once” because it is no longer.  You may occasionally stumble upon an American chestnut tree, especially small trees and saplings persisting as sprouts from the large trees that graced our landscape a century ago. Older trees, with mature fruits, are quite rare. 
 
In fact, some estimates suggest American chestnut accounted for one in four trees in some forests!  So, what happened?  In the early 1900s, a disease caused by a pathogenic fungus (Cryphonectria parasitica) was accidentally introduced with imported Asian trees. It was first recorded in New York City in 1904.  In a matter of decades, American chestnut was nearly decimated by this disease known as Chestnut blight.
 
The Carnegie Museum herbarium captures this change in our forests. 
 
This specimen of American chestnut was collected by influential Carnegie Museum curator Otto Jennings on October 21, 1922 on a field trip of the Botanical Society of Western Pennsylvania to Chestnut Ridge, near Derry Township, Pennsylvania.  Chestnut Ridge is a ridge of the Allegheny Mountains, presumably named for its (once) many American chestnuts. 
 
This specimen is from the fruit collection of the herbarium.  These specimens are different than the “standard” pressed flat specimens on paper.  Instead, they are stored to maintain their three-dimensional structure.
 
Note the note made by Jennings on the label on this specimen:
“Trees from ¼ to all killed by blight.”
 
The case of the American chestnut is an interesting one.  It served important cultural and ecological roles; some even calling a “keystone” species.  There is no doubt that the functional extinction of American chestnut ricocheted through the ecosystem, causing long-term biological changes. Many of these changes we may not know.  Yet, at the same time, despite the species importance, our forests continue.  Presumably other species have filled the functional and physical space of American chestnut. 
 
Disease and pest outbreaks in Pennsylvania’s forests continue.  Many of our critical tree species are likely to decline in coming years and decades.  Some iconic species have already declined or at risk.  These include our ash species (mortality caused by introduced Emerald Ash Borer), American beech (Beech leaf disease, Beech bark disease caused by an introduced scale insect), and eastern hemlock (mortality caused by introduced sap sucking bug, the hemlock woolly adelgid)...to name only a few threats.
 
What will Penn’s woods look like in another 100 years? 
Our collections document the past and present to inform our decisions for the future.

Fall blooms rival those of spring
 
In the northeastern United States, we often think of spring as a time for wildflowers.  But the fall is, too.  
 
It is easy to be distracted by the beautiful fall foliage, when our landscape turns brilliant shades of red, orange, and yellow.  But when many plants are shutting down for the winter, others are just kicking into gear.
 
Many wildflower species bloom well into fall, both in open areas and in the forest understory.  One group of plants are the fall blooming “asters.”  In same plant family as sunflowers and dandelions (Asteraceae), Aster was once a very large plant genus in our native North American flora (somewhere along the lines of >175 species!), but as we learned more about the evolutionary relationships of these plants, they have since been split into multiple genera (plural of genus). In fact, there is only one “true” Aster in Pennsylvania, Tatarian aster (Aster tataricus), which is actually not even native to Pennsylvania!  Regardless of the scientific name, these plants are commonly referred to as asters.  And they put on quite an autumn show in Pennsylvania.
 
Perhaps one of the most common woodland asters in Pennsylvania is white wood aster (Eurybia divaricata, formerly known as Aster divaricatus).  This specimen was collected in September 29, 1967 by N.R. Farnsworth in Pittsburgh’s Schenley Park.  This species can still be found in Schenley Park, and many parks, woodlands, and wooded roadsides across Eastern North America.
 
Fall foliage is beautiful in Pennsylvania.  But don’t forget to look down at the flowers, too!
 
Find this white wood aster specimen here: https://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11826562

Check out the “santa claus” pappus on this specimen of bull thistle (Cirsium vulgare), collected on July 26, 1966 by Leroy Henry near Woodbine (Butler county), Pennsylvania.  Leroy Henry was a botany curator at the Carnegie Museum.  All species in the genus Cirsium are known as “thistles.”  They have distinctive spiny leaves and stems, with even more distinctive purple flower heads. There are native thistles, but many are introduced, common in disturbed areas and in and around agricultural fields across the country.  Bull thistle is native in Europe and Western Asia, but widely introduced across the world, including North America.  It is considered invasive in many areas.  It is the national flower of Scotland.
 
Keep an eye out for thistles, and “santa clauses.”  Don’t forget to make a wish.
 
Find this bull thistle specimens here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11831581&clid=0
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It can’t be snow, right? It’s summer!  Maybe that is cotton falling from the sky?  Well, kind of!  It is cottonwood seeds! 
 
Perhaps you’ve seen little cotton-like white particles falling from the sky in early summer, especially around Pennsylvania’s rivers or lakes. It is a common site along the dunes of Presque Isle, for example, and in areas along southwestern PA’s rivers.  Aptly named, Eastern cottonwood (Populus deltoides) is a native tree found across the eastern United States that produce seeds that fall from high up in the canopy, attached to cotton-like strands.  These help spread the seeds farther, transporting the seeds in the breeze.
 
This specimen of Eastern cottonwood was collected by Henry T. Skinner on June 8, 1942 on the sand dunes of Presque Isle, Erie. You might notice this specimen is not from the Carnegie Museum herbarium like most of these pots. But instead, this specimen is  held at the Morris Arboretum (part of the University of Pennsylvania). Now that museum collections are being digitized, we can search for species of interest, or plants collected from certain places or by certain people, or more... that’s the power of specimen digitization.  The Mid-Atlantic Megalopolis Project, funded by the National Science Foundation, is digitizing nearly a million specimens across our region,  including Carnegie  Museum specimens.  This makes our collections all the more powerful, combining all specimens collected in the region and making them accessible to scientists and the public alike.
 
Find this and more Eastern cottonwood specimens from Presque Isle here: http://midatlanticherbaria.org/portal/collections/list.php?db=all&county=erie&local=presque&taxa=Populus+deltoides&usethes=1&taxontype=2
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Tulips in June?!
 
Your tulips may be long gone as spring has faded, but tulip tree is in full force! Though hard to catch a glimpse way up in the canopy, its flowers are just as stunning.  Completely unrelated to tulips, Liriodendron tulipifera (called tulip tree, tulip poplar, or sometimes yellow poplar) is named such because its leaves have a distinctive shape reminiscent of tulips. Found across eastern North America, Tulip tree is one the tallest and fast-growing trees native to Pennsylvania, growing up to nearly 200 feet tall!   Tulip tree is relatively shade intolerant and is especially common in young forests (early successional). However, it can still be found in older forests too.  Its tall, straight trunks can be impressive. It is a widely used wood by woodworkers,  often referred to as “poplar.”   However, it is not related to true poplars (Populus species in the willow family, Salicaceae).  Tulip tree is a member of the magnolia family (Magnoliaceae). 
 
This beautiful specimen was collected on June 6, 1920 near Trafford, Pennsylvania by Otto Jennings. Jennings was an influential botany curator at the museum for many years.
 
Find this stunning specimen here:
http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12085314&clid=0
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Plants with bladders?

This specimen was collected on May 29, 1940 by Leroy Henry along Pine Creek,  north of  Wildwood outside of Pittsburgh.  Leroy Henry was a mycologist  (studied fungi) and botanist who was curator at Carnegie Museum from 1937-1973.  
 
Aptly called “bladdernut” (Staphylea trifolia), this charismatic native understory shrub produces clusters of white flowers in the spring.  These dangling flowers develop into striking bladder-like fruit. In each “bladder” pouch are seeds.  These fruit often persist through fall and some linger through winter, though the plant is leafless.
 
Bladdernut has a wide range across eastern  North America, and can be found in relatively undisturbed forests in our area, often forming thickets.
 
Find this specimen here:
http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12232780
 

When you think spring wildflowers, this plant might not immediately come to mind.  You may think of stunning plants like white flowered trillium, with lush blooms carpeting our forests, or the yellow petals of trout lily. But do you think of false mermaidweed?!  You should.
 
False mermaidweed is a curious plant with a common name that is guaranteed to make you smile and a scientific name that is hard to spell (Floerkea proserpinacoides; also hard to say without smiling). It is quite common in Pennsylvania and widespread across the continent of North America. It is found in moderately wet forest understories.   Easily overlooked at first, but well worth a closer look. 
 
Check out this specimen collected on May 14, 1934 by Edward H. Graham in Beaver county, Pennsylvania (just down the road from what would become Raccoon Creek State Park 11 years later).
 
It might not look like much. Oh, but it is! They almost look like or bedstraw at first glance, but they can form spectacular carpets along the forest floor. The stems are fragile and weak. The flowers are so tiny and non-showy, you have to make a purposeful effort to enjoy them.
 
False mermaidweed is a spring ephemeral, meaning it produces leaves in the early spring and completes its life cycle before being shaded out by overstory trees.  Some other (perhaps more charismatic) spring ephemerals in our woods include spring beauty (Claytonia virginica) and yellow trout lily (Erythonium americanum).
 
But false mermaidweed is unlike other spring ephemerals.  Most spring wildflowers are long-lived plants (perennials).  Trillium, for instance, can live for decades.  But false mermaidweed is an annual, meaning it lives for only one year.  It germinates, grows, flowers, produces seeds, and dies...all before trees produce leaves in the spring.  By late spring and early summer, there is no trace of the species. Just seeds in the soil, waiting to germinate next spring.  False mermaidweed seedlings are among the first to germinate in the spring and are quite distinct and easy to identify, with three unique mini leaves.

​And to top that off, the tiny flower of false mermaidweed is the logo of the Flora of North America (a large, long running project documenting and describing the plans of the continent).
​
Where’s its funny name come from?  Well, like many common names, that’s complicated. But since you asked:  The plant was first named by the German botanist C. L. Willdenow in 1801, given the scientific name Floerkea proserpinacoides.  Genus Floerkea was named in honor of another German botanist  (lwith last name Flörke) and its species name indicates it “looks like Proserpinaca.”  Proserpinaca is called mermaidweed. The plant is unrelated to false mermaidweed.  An aquatic plant, Proserpinaca is called “mermaidweed” because it has two visually distinctive forms for the part of plant below the water and the part of plant above the water (hence “mermaid”).  So, that why it has the funny name, false mermaidweed.  (A fun story for your next party!).

​An ecologically, taxonomically, and culturally interesting species!
 
Find this specimen here (and 214 more!) more, including high resolution images:
 
http://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Floerkea+proserpinacoides&usethes=1&taxontype=2   ​

Find this specimen here:
​http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=1235336

​Spontaneous mints in your backyard
 
This specimen of purple dead-nettle  (Lamium purpureum) was collected on April 17, 1998 by Kevin McGowan and Meggan Scanlon near Settler’s Cabin County Park in Oakdale, PA on property that is now the Pittsburgh Botanic Garden.  As seen in the title of the specimen label, it was collected as part of a biological survey for the planning of the site, a large ongoing restoration of the formerly mined property.
 
Purple dead-nettle is probably in your backyard. Or if not, you likely don’t have to go far to find it in a lawn or sidewalk crack.   Some call it a “weed.” Or, in the case of in your lawn, “spontaneous vegetation” is a lighter hearted term. It is native to Europe and Asia but now widespread across the world, including North America.
 
Purple dead-nettle is not related to stinging nettle, despite the name.   It was named “dead-nettle” because is reminiscent to nettles (well, at least to whoever came up with the common name) but does  not have stinging hairs.
 
Purple dead-nettle is in the mint family (Lamiaceae) with square stems often characteristic of mints.  Try rolling the stem between your fingers and you’ll notice the square stems.
 
The City Nature Challenge is just around the corner (April 24-27)! The City Nature Challenge is a global event where cities come together to share the biodiversity seen in their urban areas. Your nature sightings are shared through the free community science platform, iNaturalist. If you have never used iNaturalist, the City Nature Challenge is a great way to introduce yourself to iNaturalist.  You’ll be hooked.
 
Past years have been (friendly) competitions among cities, competing for the most observations or species. But given the current pandemic, this year is different.  It is not about the number of observations you make. It is a celebration of nature, wherever you can safely be this year...which for most, is your backyard!  Or the sidewalk near your house. Or the parking lot. Or a local park. Or maybe even inside your house.
 
Keep a look out for purple dead-nettle.  You won’t have to go far!
 
Last year’s City Nature Challenge Pittsburgh 2019, this species was the 9th most observed species!
 
Or if you can’t safely be outside, you can view other observations on iNaturalist.org at any time!  You can help identify photos or just click around and go for a virtual botanical hike around Pittsburgh!
 
Or look online at Carnegie Museum’s 185 herbarium specimens of purple dead nettle, going back to 1826 in England! (though this one hasn’t yet been imaged).    Or this one growing 138 years ago collected in Beaver county.
 
However you can, there are plenty of ways to participate and connect with nature while staying safe!

“Who are you calling a pansy?”
 
This specimen of wild pansy (Viola bicolor) was collected on March 21, 2012 along the Monongahela River in California – California, Pennsylvania that is!  Allison Cusick collected this specimen. Allison is a former state botanist in Ohio and currently an active research associate at Carnegie Museum.
 
Wild pansy, also called field pansy, is in the same genus as violets (Viola. It is said to be the only pansy native to North America, though there is some debate if it was introduced.
 
This species is a relative of garden pansies, which are hybrids of different Viola species.
 
Pansies are actually pretty tough.  Blooming early and can be found in disturbed habitats like lawns and roadsides.
 
Find this specimen here: http://midatlanticherbaria.org/portal/collections/list.php?db=all&catnum=CM526628&othercatnum=1

It may be spring on your calendar...but most trees aren’t quite ready.
 
This leafless specimen of white ash (Fraxinus americana) was collected on March 20, 1919  by  E.M. Gress in “Frick’s Woods” in Pittsburgh. Frick Park is now a major city park in Pittsburgh, much loved by many.  It became a city park in 1919 (the same year this specimen was collected!), bequeathed to the city upon the death of industrialist Henry Clay Frick.  Earnest Milton Gress was the state botanist for the Pennsylvania Department of Agriculture. While we don't know for sure why Dr. Gress collected this specimen (and at least 6 others), it may be as part of property surveys for a possibly new public park.
 
As you can see from this specimen, white ash is usually still leafless this early in the spring. White ash is an economically and important species in Pennsylvania, with a wide distribution across the eastern US.  However, white ash (and other ash species) are in rapid decline due to the introduction of the Emerald Ash Borer (Agrilus planipennis), a beetle native to north-eastern Asia. The beetle lays eggs under the bark  of the species, and the larvae feed on the tree. It is causing the death of many ashes in North America and Europe. It was first discovered in the US in Michigan in 2002, and first documented  in Pennsylvania in 2012.  It is a relatively recent introduction. As an active invasion, the consequences are  still developing.  Read more here about emerald ash borer’s wide-ranging impacts to our forests:  https://www.fs.fed.us/nrs/pubs/jrnl/2019/nrs_2019_knight_001.pdf
 
Side note: The label shows the specimen was once part of the “Herbarium of Bureau of Economic Zoology, Penna. Dept. Agr. Harrisburgh, PA.”  Who knew the bureau of zoology (animals) had an herbarium!?
 
Find this specimen and the other specimens Gress collected at “Frick’s Woods” here: http://midatlanticherbaria.org/portal/collections/list.php?db=all&county=allegheny&eventdate1=March+20%2C+1919