Mason Heberling

Botanical signs of fall are everywhere, to name a few --  colorful leaves, apples, squash, pumpkins, and the many wild and cultivated fall flowers. Among the most popular plant flowers in fall are those in the genus Chrysanthemum (in the sunflower family, Asteraceae), or best known as simply “mums.” They are native to Asia, but many horticultural varieties exist. Mums have been cultivated by humans for at least several thousand years, with evidence in Chinese writings dating back to 15th century BC.
 
This beautiful mum specimen was collected in “Fall” in 1914 by John Jones at Phipps Conservatory, Schenley Park, Pittsburgh.
 
High resolution image available here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11826736&clid=0

Fall allergies causing you grief?  
 
Ragweed is a plant many people are (all too) familiar with.  Or at least their bodies are.  Common ragweed (Ambrosia artemisiifolia) is actually native to North America, but has been introduced across the world.  In many cases, this plant (or other ragweed species) are to blame for seasonal pollen allergies known as “hay fever.”  In summer and early fall, ragweed plants produce copious numbers of pollen grains, which are dispersed in the wind.  Don’t blame those insect-pollinated plants with showy flowers for your allergy troubles.  Wind pollinated plants like ragweed are your culprit. 
 
This ragweed specimen was collected by Bonnie and Joe Isaac in Lawrence county, Pennsylvania on October 8, 1995.  Bonnie is the collection manager in the Section of Botany at the museum, an active plant collector and field botanist, and an expert on the plants of Pennsylvania.
 
Although ragweed is native in the US, historical records (pollen deposited in sediment cores) suggest that this species was far less common in North America before European colonization.  This is perhaps not too surprising considering the species thrives in disturbed habitats that came with European colonization and urbanization.  A study published in 2014 by Martin and colleagues in the journal Molecular Ecology extracted DNA from nearly 500 historic herbarium specimens dating back to the 1800s to measure the genetic makeup prior widespread changes to the landscape in the late 19th century. Combined with data from recent collections, they found shifts in the genetic makeup of ragweed populations as the species was expanding in the United States. 
 
Read the study abstract here: https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.12675

​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. 

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.

​​“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.

 

Plants are an important part of the urban landscape – both those planted species and those that are wild. There are more to “weeds” than you might think.  From sidewalk cracks downtown to city parks, plants are important to the ecological, economic, and human health of our city.  Understanding what plants thrive (or not) and their roles in a healthy, functional ecosystem in cities and human dominated environments that define the Anthropocene. With a recent award from the National Science Foundation (starting this September and running for 3 years ), we will be digitizing all specimens in the Carnegie Museum’s herbarium from the Mid-Atlantic Region (PA, MD, NY, NJ, DE & Washington, DC).  That is a total of nearly 190,000 specimens!  We are partnering with an ongoing herbarium digitization initiative, the Mid-Atlantic Megalopolis Project, which includes 11 other institutions in an effort to document and understand the past, present, and future plants in urban environments.
 
This specimen of Bellis perennis, also called “lawn daisy,” was collected just outside the museum in front of the Carnegie Library by former botany curator Otto Jennings on May 26, 1909.  This member of the sunflower family (Asteraceae) is native to Europe but has since been transported across the world and has become naturalized in many areas, joining the urban flora.
 
This project will facilitate a better understanding of the often-overlooked biodiversity in the city and the plants that make up Pittsburgh, both today and 150+ years ago.
 
Expect more posts in the coming months that highlight the Plants of Pittsburgh!  

​Some species are well adapted for life in the Anthropocene, commonly found in novel, human-made habitats such as roadsides, sidewalk cracks, farm fields, dumps and industrial sites.  One such plant species that particularly well suited to city life is “quickweed” (Galinsoga quadriradiata). It has many common names, including “Peruvian daisy,” “shaggy soldier,” and “fringed quickweed.” In fact, the species was once known locally as “Pittsburgh weed.” To our knowledge, this is the only example of a non-native species that was first recorded in North America in Pittsburgh (or at least among the earliest). It was introduced here from South America sometime in the mid-1800s.  Pittsburgh weed was first discovered by the courthouse in Pittsburgh by Judge John D. Shafer (1848-1926), a prominent lawyer and dean of Law School of the Western University of Pennsylvania (now University of Pittsburgh). An avid botanist, Shafer was also a founding member of the Western Pennsylvania Botanical Society. The specimen pictured here is one of the earliest (if not the earliest) specimen collected in North America, well outside its native range. It was collected 1869 in along the “Ridge St” railroad tracks in Allegheny City, which has since been annexed by Pittsburgh (now the North Side).  Keep a look out for this interesting species throughout the city, especially along sidewalk cracks and at the base of street signs and electric line poles.  It is now a common weed, and can be found in nearly every major city all over the world.

Below: Close up of original specimen label from the earliest collection (that still exists) of the species in Pittsburgh, collected in 1869.

Below: "Pittsburgh weed" (aka "quickweed") taken on October 13, 2017 in the lawn near the Carnegie Museum of Natural History.

​Nancy Hanks Lincoln (mother of Abraham Lincoln) died on Oct. 5, 1818 from “milk sickness.”  Milk sickness is caused by poisoning after drinking milk from cows that have eaten the plant white snakeroot (Ageratina altissima).  Also known as “puking fever” or simply “the trembles,” early European-American settlers in the Midwest initially thought milk sickness was an infectious disease.  It was soon realized that the unidentified illnesses were caused by drinking milk from cows that ate white snakeroot, which contains the chemical tremetol, a toxin which causes weakness, pain, vomiting, abdominal pain, and can lead to coma and death.  The cattle of these early settlers often wandered into the forest to graze, seeking additional forage outside limited pastures.  However, milk sickness is very uncommon today due to modern farming practices and cows rarely have access to eat this plant.
 
White snakeroot is a fall blooming, shade-tolerant species found in forests across the Eastern US, and commonly found throughout southwestern PA.  This specimen pictured was collected in 1998 in southwestern Indiana, about 90 miles north of the Little Pigeon Creek Community, where Abraham Lincoln’s family lived.

Another fall blooming aster!  ​Collected on October 6, 1896 (same year Carnegie Museum was founded!), this specimen was found by early museum botanist John Shafer on Jack’s Island, a small island on the Allegheny River (between Harrison Twp and city of Lower Burrell).   Despite the name, New England aster can be found across eastern North America.  Along with many other species in the genus Aster, this species was recently reclassified in the Symphyotrichum genus.  Symphyotrichum novae-angliae is a perennial (lives for several years) with beautiful deep blue-purple flowers.  Like other plants in the sunflower family (Asteraceae), the “flowers” are actually a cluster of flowers (heads) composed of many flowers, with “ray” and/or “disk” flowers.  

North America used to have over 150 species in the genus, Aster.  But now only one species remains.  That isn’t because they went extinct, but instead, they were re-named.  Many of these species are still referred in general as “asters.”  Collected on September 22, 1900, this specimen was found in Fern Hollow, Frick Park, Pittsburgh by early museum botanist John Shafer. Eurybia divaricata (formerly Aster divaricatus) is commonly known as “white wood aster.”  This beautiful fall blooming plant (like many asters) is a common native in eastern US forests.  So why the new name?  Taxonomy (the science of classifying organisms) is an ever-changing science, subject to revision as more research is done, especially at the molecular (DNA) level.  As we understand how organisms are related, we can better understand the history of life on earth.  Taxonomic studies of plants often lead to splitting of one species into many or the lumping of many species into one. In some cases, a “new” rare species may be have been hiding under our noses, previously grouped with another species. These studies are important for the conservation and protection of vulnerable species. We must know what these species are to actually protect them!
 
Like most herbaria (plural for herbarium), the Carnegie Museum herbarium is organized by genus within families.  Earlier this year, collections manager Bonnie Isaac and a team of interns and volunteers reorganized the sunflower family (Asteraceae), one of the largest families of flowering plants.  After a month of reorganizing and renaming folders, the work is still ongoing.  No surprise, as this family is represented by over 51,000 specimens (or about 10% of the entire collection)!  Ongoing taxonomic rearrangements like these are just one reason why the work of herbarium staff is never done.