Mason Heberling

​Many invasive species in our region were ironically first introduced intentionally.  The tree-of-heaven (Ailanthus altissima) is one such example, originally praised with enthusiasm as a lovely garden tree, fast growing, well behaved, resistant to pests and pollution – therefore an excellent urban street tree.  Tree-of-heaven was introduced first to Europe from northern China, then to North America in the 1780s to a garden in Philadelphia.  Decades later (and several additional introductions), it grew in popularity to become widely available and adopted for use in town and city plantings through the mid-1800s, including New York City.  By the 1900s, it was widely naturalized in both urban and rural areas across much of the United States.  It is now recognized by most states as an invasive species.  Tree-of-heaven was the namesake tree in Betty Smith’s 1943 classic novel, A Tree Grows in Brooklyn.
 
This specimen was collected by Sue Thompson and Lawrence LaSpoda on September 28, 1983 in Panther Hollow, not far from the Carnegie Museum in Pittsburgh.
 
Keep an eye out for this weedy tree, which is common throughout the city and along highways.  Its seeds are especially noticeably this time of year and persist on the tree into the winter.

​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.