Mason Heberling

​Herbarium specimens are both an art and a science.  This fact is no more apparent than in the collaborations between Andrey Avinoff and Otto Jennings, which culminated in the 1953 book Wildflowers of Western Pennsylvania and the Upper Ohio Basin.  Jennings was a longtime curator of botany, professor at University of Pittsburgh, and served many roles at the Carnegie Museum (including director from 1945-1949). Avinoff was a lepidopterist (studied butterflies) and artist, who was Director of the Carnegie Museum from 1926-1945. The book features a detailed, scientific manual describing plant species found in the region written by Jennings, along 200 watercolor paintings of a subset of these species by Avinoff.  Jennings would travel across Western PA in search of the perfect specimen to return to the museum for Avinoff to paint while still fresh and unwithered.  Avinoff is said to have dropped everything he was doing upon Jennings’ return, and stay through the night to paint the flowers from still life.  Avinoff estimated that it took him about 1,600 hours to paint them all.
 
Some of these specimens were then pressed and remain in the Carnegie Museum’s herbarium today.  We know of 50 specimens that were used by Avinoff for his paintings.   
 
This specimen of squarrose goldenrod (Solidago squarrosa) is one of those specimens.  It was collected by Otto Jennings on September 21, 1941 on a ledge along the river bluffs near Bell’s Landing, Clearfield County, Pennsylvania. 
 
Both of scientific and cultural value, this specimen has a rich history, much more than “just” dried plants on paper.  While we know the history behind this particular one, each specimen has an important scientific and cultural story to tell. 

Dr. Avinoff, referring to his wildflower paintings -- 
​“These were my guiding principles:
(1) accuracy in form and color;
(2) portrayal of the individuality of the plant as to the character, position, arrangement, and venation of the leaves and the texture of their surfaces;
(3) decorative arrangement, composition, and spacing;
(4) strictly water color technique—only transparent pigment and no opaque colors, no white paint anywhere, not a single stroke used in the high lights. The white is the paper and all light parts are lighter washes of the pigment—thoroughbred aquarelle has been observed throughout.”

​This digital specimen is now online!: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11795987&clid=0

We've embarked on a three-year project to digitize nearly 190,000 plant specimens collected in the region, making images and other data publicly available online. This effort is part of the Mid-Atlantic Megalopolis Project (mamdigitization.org), a network of thirteen herbaria spanning the densely populated urban corridor from Washington, D.C. to New York City to achieve a greater understanding of our urban areas, including the unique industrial and environmental history of the greater Pittsburgh region. This project is made possible by the National Science Foundation under grant no. 1801022. 

You can get to see plants from all over the world without ever leaving the herbarium.   Herbaria are powerful resources that enable research that would otherwise not be possible, comparing plant species collected from across the world, at different times of year.
 
This specimen of Japanese knotweed (Fallopia japonica, formerly known as Polygonum cuspidatum) was collected in China on Sept 14, 1989 by Q.X. Wang and J.L. Sun.
 
Even if you’ve never been to East Asia, this species might be familiar to you.  Although native to China, Japan, and Korea, Japanese knotweed is now common across much of the temperate world, including the United States and Europe.  In Pittsburgh, Japanese knotweed (and related introduced knotweed species) form dense stands along rivers, streams and roadsides.
 
Specimens collected from both the native and introduced ranges can be compared to better understand plant invasions.  For example, do invasive species look the same in their home range?
 
Although Collected On This Day posts tend to be biased towards specimens collected in Pennsylvania, the Carnegie Museum herbarium includes specimens from many countries across the world.  In fact, about 1/3 of the 530,000+ specimens are from outside the United States. 
 
How do these species from far away regions end up at the Carnegie Museum?  Many are from expeditions from botanists affiliated with the museum – much in the same way locally collected specimens become part of the collection.  But many others are obtained through exchange with other herbaria.  Many plant collectors often collect duplicate specimens to send to several herbaria.  Most herbaria have exchange programs, where specimens (usually duplicates) are exchanged between institutions.  This practice functions to build the collection to include new species and specimens.  But it also has an important function to safeguard the future of the data.  In the case of damage (such as pest outbreaks or even fire, in the recent devastating case at the Museu Nacional in Brazil), having specimens spread across several institutions helps ensure the future of specimens.
 
Note the label on this specimen shows this specimen was at one time associated with the herbarium of the Shanghai Museum of Natural History. 

​47 of the 96 specimens of Japanese knotweed in the Carnegie Museum’s herbarium were collected outside of the United States.

​It is now a common plant in forests across Pennsylvania, but it wasn’t always.  This specimen of Japanese stiltgrass (Microstegium vimineum) was collected on September 7, 2017 by Mason Heberling (me!) at Trillium Trail, Fox Chapel, PA.  Native to East Asia, Japanese stiltgrass is an annual grass that is said to have first been introduced accidentally to Knoxville, Tennessee around 1919, used as packing material for porcelain dishes from China.  It has since become a major invasive species, spreading across forests of Eastern North America.  It is commonly found along trails, forest roads, and floodplains.  It has been shown to be facilitated by deer overabundance.  A recent study of unconventional gas well pads (such as “fracking”) in Pennsylvania by Penn State researchers found that recent hydraulic fracturing activities facilitates stiltgrass invasion (Barlow et al., 2017 Journal of Environmental Management).  Japanese stiltgrass is especially common in common disturbed moist forests, where available light in the understory is higher.  Therefore, it often carpets the forest floor in disturbed forests.  High densities of deer have also been shown to facilitate stiltgrass invasions.  In fact, much of this research was done at Trillium Trail by Susan Kalisz (then at University of Pittsburgh, now at University of Tennessee Knoxville).  Read more here: https://kaliszlab.weebly.com/uploads/2/5/1/2/25120034/knightsmithdaviskalisz-na_j2009.pdf   They used fences to exclude deer and found that stiltgrass was not present in fenced plots, but abundant when deer were allowed access. The Kalisz lab actively remains at Trillium Trail.
 
Although collected only two years ago, I was surprised to find that this specimen was the oldest Japanese stiltgrass specimen collected in Allegheny county!  There is a chance it had been collected earlier and exists in another herbarium. It was said to be uncommon (possibly absent) at Trillium Trail until 2002. 
 
What will our forests look like in another 10 years?  Herbarium specimens are important, verifiable sources to document our changing flora.  And ultimately, help conserve our flora.

Once you learn to recognize this grass, you are likely to see it everywhere in forests and forest edges in Western Pennsylvania. It is especially obvious in the Fall, when it flowers and has reached its peak growth. Note the faint white line along the center of the leaf blades.

​Microstegium vimineum carpeting the forest floor outside deer fences at Trillium Trail.  

Wildflower specimens collected at Compton's Mills in 1952.
Welcomed signs of late summer and fall pictured below (left to right): common boneset (Eupatorium perfoliatum), tall ironweed (Vernonia altissima), wreath goldenrod (Solidago caesia). 

​These specimens (and more) were collected on September 6, 1952 near Compton’s Mills (near Salisbury, PA, Somerset County) by Leroy Henry and Werner Buker. Henry was a long time Curator of Botany at the museum (1937-1973), and Buker was a math teacher at Perry High School, who was also a very active botanist at the museum.  Collectively, they collected nearly 50,000 specimens in the Carnegie Museum herbarium!
 
These specimens are part of a larger project ongoing in the Section of Botany at the Carnegie Museum.  Starting last year, we are revisiting historic sites across Western Pennsylvania, where former botanists have collected.  We are revisiting these sites in order to record and monitor biological change in the Anthropocene.  Are the same species present? (local extinction or persistence) Are new species present? (newly introduced invasive species)
 
We are also recollecting specimens from these historic sites to compare specimens collected decades to a century ago, to those collected today. For example, how are species affected by climate change? Are species flowering earlier? How are plant communities affected by invasive species and introduced pests? These are just a few of the many questions that can be answered.
 
With generous permission of the current landowner, we are able to recollect specimens at Compton’s Mills. Compton’s Mills is a site of a family-run historic grist/flour mill built in 1872 on the foundation of an even earlier mill. We have done some recollections at this site last spring, including specimens of the endemic Appalachian violet (Viola appalachiensis).  Compton’s Mills of also of special importance, as specimens collected from this site were used by Leroy Henry to formally describe the species new to science (known as “type” specimens.  Read about our recollection in Spring 2017 here: https://www.masonheberling.com/collected-on-this-day/collected-and-recollected-on-this-day).
 
This year we are revisiting in the late summer/early fall.
 
With data from Compton's Mills, in addition to repeatedly revisiting other sites across Western Pennsylvania, we will be able to document and understand a century of past, present, and future impacts of humans on the landscape-- a hallmark of the Anthropocene.

​Some of our first recollections were featured in the We Are Nature exhibition.  Although this exhibition recently ended, specimens from this project will remain on display in the Hall of Botany.

​
Spring wildflowers in August? It turns out that quite a few of the spring wildflower species that carpet out forest understories in the spring actually remain through the summer, and some even into early fall! This specimen of bloodroot (Sanguinaria canadensis) was collected near Port Stanley, Ontario, Canada on August 30, 1913 by Otto and Grace Jennings.  Otto was a longtime curator of botany at the Carnegie Museum and Grace was a botanist and curatorial assistant at the museum.  They had several expeditions from early 1900s through the 1930s.  There are 4,362 specimens currently in the collection collected by them.

Photo below: Spectacular display of bloodroot at Trillium Trail, Fox Chapel, PA on April 23, 2015.

Bloodroot is one of my favorite spring wildflowers, among the earliest to bloom in our region.  It is aptly named after the color of its belowground perennial storage organ, called rhizome.  Many perennial wildflowers have these belowground structures for storage of carbohydrates, which accumulates through photosynthesis for reproduction (flowering/fruiting) and early growth the following year.  Bloodroot produced toxic alkaloids (sanguinarine) and has many medicinal and traditional uses by Native Americans.  In fact, it is FDA approved as an antibacterial agent in toothpaste, but has since been regulated due to suggested links to oral cancer. It was also an important plant dye.

Photo below:  "Bloody" belowground storage organs of bloodroot. 
​Credit: Slayerwulfe [CC0], from Wikimedia Commons

This species can be seen in the Pittsburgh region and throughout western PA and, most noticeably in the spring, before trees leaf out, when it has a magnificent display of flowers.  However, its fruit and leaves can remain well into summer.
 
In our study of wildflowers at Trillium Trail (Fox Chapel, PA), we found bloodroot acquires about 1/3 of its annual carbon  in the summer (energy source for plants through photosynthesis) , and about 2/3 in the spring (before tree leaf out).  This study was recently published in the journal New Phytologist. Read the full paper here: https://rdcu.be/5zo7

Drawing by Allison Heberling (my awesome spouse!)

Knotweeds collected at the 7th Annual Knotweed Festival in Blairsville, Pennsylvania.
Banks along Conemaugh River, August 11, 2018.  
Left: Giant knotweed (Fallopia sachalinensis); Right: Bohemian knotweed (Fallopia x bohemica).

​A few weekends ago, I went to the 7th annual Knotweed Festival in Blairsville, about 40 miles east of Pittsburgh in Indiana County.  Aside from reading a brief advertisement, I knew little about the festival before going. But, given I study non-native plant invasions, I had to go to a celebration named after a local weed that is a focus of my research! And this invader is one of the most aggressive and widespread ones in western Pennsylvania – Japanese knotweed.
 
Native to East Asia, Japanese knotweed (Fallopia japonica) is a large herbaceous perennial that was first introduced as to the U.S. in the late 1800s as an ornamental.  As its name suggests, it eventual spread well outside of gardens to become a major nuisance. More troubling, the spread of the species displaces native vegetation and disrupts the natural function of the ecosystem.  The plant has thick hollow stems that somewhat resemble bamboo, although they are not related (knotweed is in the buckwheat family, Polygonaceae; bamboo in the grass family, Poaceae).  Knotweed spreads through persistent belowground structures called rhizomes (belowground stems), as well as by seed.  Small fragments of rhizomes can be washed downstream and easily establish, often forming dense stands along Pittsburgh’s many streams and rivers. Knotweed is among the most economically and ecologically problematic invasive plants in Pennsylvania.
 
So, why name a community festival after this invasive plant?!  Despite the dislike for the plant, the community of Blairsville named the festival partly as a tongue-in-cheek sentiment for the plant that has taken over the landscape and partly to recognize the weed as embedded into the local culture. The nearby Conemaugh River that runs throughs Blairsville has been transformed by this non-native species, completely covering the banks with stands so dense they completely block the view of the river along the community recreational trail.

My family and I had a great time at the festival, visiting local craft and food vendors, musicians and other entertainment, a monarch butterfly display, and complete with a parade.  I even bought soap made from the rhizomes and stems of knotweed collected by the river. 

​ At first, I had mixed feelings about naming a festival after an aggressive invasive plant known to cause ecological harm. On one hand, it embraces the nature around us – whether we like it or not, non-native plants are part of the landscape around us. The global movement of plants around the globe is one of the defining features of the Anthropocene, the current era of pervasive human influence on the environment and Earth’s systems. But, on the other hand, naming a festival after an invasive species normalizes plant invasions and perhaps even embraces the change to the landscape as a good thing.  Despite my initial mixed feelings, I think the festival is a great community gathering that has the potential to raise awareness about the presence of the invasive plant in our community, its ecological effects, and in turn, nature around us (native and non-native).
 
It turns out there are more than one species of invasive knotweed in western PA: Japanese knotweed (Fallopia japonica), Giant knotweed (Fallopia sachalinensis), and a hybrid between the two species, Bohemian knotweed (Fallopia x bohemica).  The hybrid was only recognized in the past several decades and likely originated when these two species “met” after they were introduced in Europe.  The three species are visually similar.  Giant knotweed can be distinguished by its large (usually much larger than your hand), heart-shaped leaves. Japanese knotweed and the hybrid Bohemian knotweed are much more difficult to distinguish, with much variation in leaf shape.  Japanese knotweed tends to be rounder in shape, while the Bohemian knotweed is intermediate between the other two species in leaf shape and size.  The leaf hairs are sometimes the only definitive identifying feature.

​While I was at the Knotweed Festival, I collected some knotweed specimens for the Carnegie Museum’s herbarium. Along the Conemaugh River in Blairsville, I collected both the Giant knotweed and Bohemian knotweed (the hybrid).  But, I did not find any Japanese knotweed. (I suspect my knotweed soap is actually made from Giant knotweed, after all.)
 
The earliest herbarium specimens from Indiana County were collected in 1952 along the Conemaugh River in Saltsburg (not far from Blairsville).  Interestingly, these specimens were of Giant knotweed and Bohemian knotweed – the same species I collected.

Did you know Queen Anne’s lace is closely related to the carrot in your garden?  In fact, it is also called wild carrot. This specimen of Queen Anne’s lace aka wild carrot (Daucus carota) was collected in Coudersport, Pennsylvania (Potter county) on July 28, 1944 by Thomas K. Barrie.
 
Queen Anne’s lace is a common weed throughout the temperate world.  Its blooms are a sign of summer in Pittsburgh.  Not only is it in the carrot family (Apiaceae), but in fact, domesticated carrots are a cultivar of a subspecies of Queen Anne’s lace – Daucus carota subsp. sativus. 
 
Carefully pull this species out of the ground and you’ll find a hefty, fleshy tap root that looks and smells like the carrots we all know. 

Its white umbrella like clusters of flowers (called "umbels") are characteristic of the carrot family (Apiaceae), which also includes other well know species in our area such as poison hemlock.
 
Queen Anne’s lace is native to temperate Europe/Asia and was introduced to North America.  It is now widely naturalized in fields and roadsides.

Herbarium specimens can provide insight into plant-insect interactions.  For instance, many specimens show obvious signs of insect damage to the leaves or flowers.  Many other specimens, upon closer inspection under magnification, show damage that is much subtler.  Sometimes, even the larvae or insects were also pressed with the plant!  Some of this damage may have happened from pests in the herbarium that occurred over decades of storage.  Damage from herbarium pests is a serious concern and collection managers are also conservators of these archives, keeping a vigilant eye out for damage from the elements (such as light, temperature, humidity, water, and other chemicals) and introduced pests (such as mold and insects).  However, damage that occurs in the herbarium is minimized for long term preservation and luckily, insect damage that occurs in the herbarium is often easily distinguished from herbivory that happened in the wild, before the plant was collected, dried, pressed, and added to the collection.
 
Few studies to date have used the herbarium record to understand the ecology and evolution of plant-insect interactions. However, there are several pioneering studies at the frontier of this novel use of these collections.
 
This specimen pictured above of wild parsnip (Pastinaca sativa) was collected by Leroy Henry on July 17, 1968 along the Pennsylvania Turnpike not far from Pittsburgh.  Leroy Henry was an influential Curator of Botany at the Carnegie Museum from 1937-1973, having collected thousands of specimens in the herbarium.
 
In addition to the “standard” herbarium label that gives information on what the specimen was first identified as, where it was collected, who collected it, etc., check out another typed label affixed to this sheet.  This annotation label indicates two seeds were removed from for chemical analysis in 2005.  Annotation labels are commonly added to specimens years to centuries later to note its use in a study, a new identification, and/or part of the specimen was removed.
 

​
This specimen was one of many specimens included in a study on wild parsnip by Zangerl and Berenbaum published in 2005 in the high-profile journal Proceedings of the National Academy of Sciences (PNAS).  
 
Wild parsnip (Pastinaca sativa) was introduced to the United States from Europe centuries ago and has since spread to become invasive.  The species is a member of the carrot family (Apiaceae).  Like many other species in this plant family, wild parsnip produce phototoxic chemicals called furanocoumarins, which protect the plant from insect herbivory.  These compounds also cause major skin irritations in humans, reacting with sunlight to cause nasty rashes.  This group of chemicals is of the same fame of giant hogweed, poison hemlock, and other well-known toxic plants in the United States.
 
Zangerl and Berenbaum (2005) analyzed herbarium specimens collected over the past 150+ years.  These specimens were collected from before wild parsnip was widespread in the US and compared those to specimens collected more recently, after the species was widely established.  A major herbivore, the parsnip webworm (Depressaria pastinacella) was also accidentally introduced in the mid-late 1800s.  The authors found that as rates of webworm attack increased, so did the toxicity of wild parsnip.  Specimens from 1850-1889 (early stages of introduction) had lower levels of the toxic furanocoumarins than plants collected more recently, as well as than specimens collected in their native range (Europe), where the parsnip webworm is also native.
 
There is so much known and unrealized potential in herbarium specimens.  This particular specimen was not collected with the intention of studying the ecology and evolution of plant-insect interactions.   This study helped inform our current and future use of biological control agents to manage introduced species.
 
These unanticipated uses (often decades to over a century after a specimen was collected!) illustrate the incredible power of natural history collections.
 
See an excellent paper by Meineke et al. just published on this topic (including quantifying the effects of climate change on plant herbivory through herbarium specimens): https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecm.1307.
 
Check out the cool parsnip webworm study here: http://www.pnas.org/content/102/43/15529

Wild parsnip (Pastinaca sativa) in an unmowed roadside median next to Bloomfield Bridge, Pittsburgh PA on June 29, 2018.

​​“This is, perhaps, the most execrable weed that has yet invaded the farms of our country.” 
William Darlington (1859) American Weeds and Useful plants, 2nd ed. 
 
This “execrable weed” described in the quote above by Darlington over 150 years ago was Canada thistle, Cirsium arvense (sunflower family; Asteraceae).
 
This particular specimen of Canada thistle was collected by Walter Zanol on July 14, 1990 near Tarentum, Pennsylvania (Allegheny county). 
 
Canada thistle is a common weed in agricultural fields, disturbed areas, and roadsides in Pennsylvania and across the world.  Although the common name suggests it is from Canada, this is misleading, as the species is from southeastern Europe and eastern Mediterranean.
 
It was among the earliest introduced plant species in North America by European colonists, with records suggesting as early as the 1600s.  It was probably introduced accidentally as a contaminant in crop seed.  It has since spread and become invasive in many US states and Canadian provinces. It remains a major agricultural pest today.
 
By 1851, it was already regarded a “most troublesome [sic] weed, which is extremely difficult to eradicate” in Pennsylvania (Knoll, 1851).
 
It is a weed of many major crops, causing economic harm through reduction of crop yields.  It spreads both sexually (through seeds) and asexually (through underground rhizomes).  It is not uncommon to see many individuals of this species forming dense patches in fields or along the road.  These patches are likely connected belowground (or once were connected).  Because of this attribute of spreading via creeping lateral roots, it is also known as “creeping thistle.”
 
Its purple flowers and spiny stems/leaves are similar at first glance to many thistles, but its horizontal, creeping lateral roots make this species easily distinguishable from the many other non-native and native thistles in Pennsylvania.
 
Keep an eye out for this species.  It can be spotted throughout Pennsylvania this time of year, often forming dense stands that are going to seed.  Their seeds go airborne, looking almost like snow or cotton flying through the air.

 

Did you know that one of the earliest Presidents of the United States lived in southwestern PA?  The American soldier and politician Arthur St. Clair, who lived in the Ligonier Valley near Latrobe, Pennsylvania, was President two years before George Washington was! Well, sort of.  The US Constitution wasn’t drafted until the 1787, over ten years after Independence Day 1776.  Before that, under the Articles of Confederation, there was a Confederation Congress.  Arthur St. Clair was elected President of the Continental Congress in 1787. 
 
These patriotic specimens of American Bugbane (Actaea podocarpa, formerly Cimicifuga americana) were collected on July 9, 1999 in the Loyalhanna Gorge (Rt. 30 aka the Lincoln Highway runs through it between Greensburg and Ligonier, PA), near where Arthur St. Clair owned property and lived the later years of his life (now known as Saint Clair Hollow).  In the buttercup family (Ranunculaceae), American bugbane, also called mountain bugbane, is a forest understory herb similar in appearance to the more common black cohosh (Actaea racemosa).  The species is currently listed as threatened in Pennsylvania.
 
Arthur St. Clair was born in Scotland in 1737 and fought with British troops in the American colonies during the French and Indian War.  After the war, he settled in Ligonier Valley and was the largest landowner in Westmoreland County at the time.  He was later a American colonel in the Revolutionary War.  After America gained its independence, he was elected a delegate to the new Confederation Congress (governing body under the Articles of Confederation that pre-dates the Constitution).  He served a one-year term as President of the Continental Congress in 1787, during which time the Northwest Territory was created.  He later became governor of the Northwest Territory (large area which are now Midwest states).  After retiring, he returned to live out his days in the Loyalhanna Gorge (between present day Ligonier and Greensburg, not far from Idlewild Park).  He died in poverty in 1818.
 
Many towns in Pennsylvania and the Midwest are named after Arthur St. Clair, including Upper St. Clair near Pittsburgh.
 
A lot of history in Western Pennsylvania!
 
Happy 4th of July!