HEBERLING LAB

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

Each specimen has a story. Some specimens are of particular scientific importance because of their biology and the data they provide (representing a unique, endemic, rare, or threatened species for example).  Other specimens are fascinating because of the story behind of the cultural story behind the specimen, whether it be the collector or the context in which it was collected.  And some specimens are of both of biological and cultural interest.  This recently stumbled upon specimen of olive (Olea europaea) is one of those specimens, in my opinion.
 
Olive trees are iconic plants that are native to the Mediterranean Basin but have been widely cultivated by humans for at least 7,000 years. Olive has many uses by humans, both for food (olive oil, olives, etc.) and for its use in rituals and symbolism (as an example, olive branch as a symbol for peace).  Olea europaea has a rich background in world religions, with references in ancient Greece, Rome, and mentioned in throughout the Bible and in Islamic holy texts, among others.
 
This specimen includes much more than the plant itself.  The label reads “BIBLE PALESTINE PLANTS” and even includes a bible reference, along with the other information that is conventionally on herbarium specimen labels: collected in Jerusalem, 3- 5 meters tall, noting “everywhere cultivated.”  Dated May (but no year).  The specimen includes a newspaper clipping (source unknown) about the species in the context of the Bible.  No collector is given, but it says “The American Colony, Jerusalem.”

​​What is the “American Colony?”  A quick google search shows that it is now a fancy hotel in Jerusalem.  But before that, it was the site of a Christian utopian society.  The colony was established in 1881 by Americans Anna and Horatio Spafford, who left Chicago after the Great Chicago Fire in 1871. A group of Swedish Christians also joined the group later.  The group did much community outreach and other activities until the 1950s. 
 
So where did this specimen come from?  Why was it collected?  When was it collected? By whom? All of these questions aren’t entirely clear.  Super intrigued, I dug up the accession records when this specimen was donated to the museum.

​The specimen was donated as a gift in 1921 by Lewis S. Hopkins of Kent, Ohio.  The accession records state “A set of ‘Bible Palestine Plants’ as put out by The American Colony, Jerusalem. 70 specimens.”  Lewis S. Hopkins (1872-1945), was a professor of botany at Kent State Normal School (now Kent State University).  He was also a member of the Botanical Society of Western Pennsylvania.  So, we still don’t know exactly when this specimen was collected (or by whom). Given the newspaper clipping and Bible verse with this specimen, I’m guessing it was used as an education tool. This specimen certainly has some history!
 
This species was also the focus of one of the coolest uses of herbarium species to date. In 1993, Beerling and Chaloner published a study where they measured the stomata (tiny pores on leaves for gas exchange) on Olea europaea leaves, using herbarium specimens dating from the PAST 3,000 YEARS!: 1991, 1978, 1818, pre-332 BC, and 1327BC.  The oldest specimen was not a herbarium specimen in the traditional sense, but leaf material from a funeral wreath from King Tutankhamun (“King Tut” of ancient Egypt fame), now archived at the Kew Gardens, London. Stomatal density (the number of pores per area) can provide key insights into past climates and plants responses to the environment. Plants respond to increased atmospheric carbon dioxide concentrations with fewer stomata. Knowing these responses in plant species alive today, this theory linking stomatal density and other leaf traits to the environment has been applied leaf fossils to reconstruct climates when the dinosaurs reigned. 
 
This jaw dropping study was published in the journal Annals of Botany in 1993.  

Many studies have since measured stomata using herbarium specimens and it remains an important use for herbarium specimens, providing critical insights into past, present, and future ecosystems.  BUT, using specimens dating back 3,000 years connected to Ancient Egypt, this study was no “ordinary” stomatal density study.
 
This classic study on stomatal densities using herbarium was the initial motivation for this Collected On This Day blog post...I just stumbled upon the unique American Colony story in the process!

Specimen with no leaves! These twigs of white ash (Fraxinus americana) were collected in 1926 by J.K. Doutt along Squaw Run, PA.  Many specimens in the herbarium were collected from Squaw Run, especially in the late 1800s/early 1900s. Squaw Run is a tributary of the Allegheny River, that runs through Fox Chapel and O'hara Townships. Specimens without leaves are not common, and it is unclear what the exact motivations behind this collection was.

White ash (Fraxinus americana) is a common tree in forests across the Eastern US.  They are currently threatened by the Emerald Ash Borer (Agrilus planipennis), an invasive beetle that was accidentally introduced from Asia.  It was only detected in North America in 2002, and not in Pennsylvania until 2007!  It has the potential to cause our native ash trees (all native species in the genus Fraxinus) to extinction, rivaling the impacts of the Chestnut Blight on American chestnuts in the early 1900s.