Mason Heberling

Happy Thanksgiving! And what’s screams fall more than pumpkin?
 
And this specimen isn’t just any specimen – it is the museum’s first official Anthropocene collection. A 2,090.5 pound squash, in fact. The Anthropocene, or Age of Humanity, is the proposed current time period marked by pervasive and long-term human impact on the Earth’s systems. The mark of human influence is now so great, that the effects will be present in the geological record millions of years from now. The Anthropocene is a core focus for the museum, drawing together many areas of research, education, and scholarship. These Anthropocene initiatives were launched, in part, through the 2017-2018 exhibition We Are Nature: Living in the Anthropocene. At the time of the exhibition’s opening, a gigantic squash was on display in the museum’s courtyard. This 2,090.5 pound pumpkin is a striking visual of the influence of humans on plant evolution in the Anthropocene.
 
But these huge pumpkins are not easy to grow.  This specimen was from a plant grown in Ellwood City, PA by Dave and Carol Stelts. When they came to the museum to harvest seeds for next year, Bonnie Isaac, Collection Manager of Botany, collected a specimen for the herbarium. As you might guess, even the pieces don’t fit nicely on a typical herbarium sheet, but instead stored in the 3D fruit collection.
 
Species in the genus Cucurbita (including pumpkins, gourds, squashes) were domesticated by humans in North America about 10,000 years ago.  That is, they were cultivated in gardens, likely first selected for the use of their durable rinds (anthropological evidence for gourds used as containers for drinking) and later as a food source. Most Cucurbita species went extinct around this time, coinciding with the extinction of large mammals that these species relied upon to spread their seeds.  Their fruits were unpalatable to the smaller herbivores that did not go extinct. Ironically, it is human hunters, paired with climate change, that led to the extinction of large herbivores in North America.  Modern day pumpkins have adapted to the Anthropocene.
 
This Anthropocene specimen isn’t your Halloween jack-o-lantern or pie pumpkin, which is Cucurbita pepo, but the related Cucurbita maxima, which can be grown to enormous sizes with skill and effort.
 
Find this specimen and more here: http://midatlanticherbaria.org/portal/collections/list.php?db=328&catnum=CM312111&othercatnum=1

Cranberries are a holiday staple. Fresh or canned, the choice is yours. But where do they come from? 
 
The cranberry on your table is most likely the American cranberry (Vaccinium macrocarpon), a short trailing evergreen shrub native. The species is native to northeastern/northcentral North America. They are grown commercially in human-made ponds (often called cranberry bogs) that are well irrigated.  They are harvested in two ways.   If the fruit is used for juices, sauces, or  dried, the ponds are flooded in the fall for harvesting (the fruit floats).  For use  as fresh cranberries,  the fruit is harvest dry.
 
Check out this cool specimen of cranberry, collected by Millie Turner in 1928 between Saxonburg and Freeport, Pennsylvania near Cypher farm.  Cypher farm still exists today,  operated by the same family  for over 100 years.
 
What is especially neat about this specimen is a note attached that reads “...80 ten quart  pails of these berries were picked at one time from  this bog.”
 

Now that’s a lot of cranberry sauce!  
 
Find this specimen and more cranberries here: 
​ http://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Vaccinium+macrocarpon&usethes=1&taxontype=2

Look carefully in the fall diorama of a bog in northwestern Pennsylvania in the Hall of Botany to see cranberries as they’d appear in the wild.

Which hazel? This one!
 
Witch hazel (Hamamelis virginiana) is such a cool species for many reasons, but especially because of its unique flowering phenology. Witch hazel has striking yellow flowers in the fall, blooming as the leaves drop. Check out this flowering specimen collected in the back of Allegheny Cemetery (Pittsburgh) on November 16, 1884 by John Shafer, who would later be the first custodian of the Carnegie Museum herbarium (1897-1904) before moving to the New York Botanical Garden. Shafer graduated from the Pittsburgh
School of Pharmacy at the age of 18 (now part of University of Pittsburgh) and many of the oldest specimens collected in and around Pittsburgh were collected by him.  Shafer was influential in the early growth of the Carnegie  Museum herbarium, including facilitating donations of specimens dating back to early 1800s and donating his own collection.  You can see from this label that this specimen was from the herbarium of the Botanical Society of Western Pennsylvania (which became part of the Carnegie Museum herbarium).
 
Find this specimen and more here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12026676&clid=0

Who needs leaves?
 
This red maple (Acer rubrum) specimen was collected on November 13, 1915 by former Carnegie Museum curator Otto Jennings on a rocky back north of Finleyville, Pennsylvania.
 
Something about herbarium specimens that are just branches, with no leaves or flowers.  But the flowers and leaves are there…well, sort of.  
 
Check out the nice buds on this specimen. Many deciduous tree species in temperate areas (like Pennsylvania) have “preformed” buds.  These buds are produced in the summer, packed with leave and/or flower tissue. You can see these buds swell during the winter in preparation for budburst.  Then when the conditions are right (like temperature and chilling time), the plant is ready to go! The cells don’t need to be made, and spring budburst is all about expansion.

It is fun to think of what is inside these buds.  There is a lot going on in there. Keep an eye on them on the trees in your neck of the woods. Many are rearing to go, riding out the winter.
 
Find this specimen and search for more here.

A bittersweet specimen, in more ways than one...  

This specimen of American bittersweet (Celastrus scandens) is the most recent record of the species in Allegheny county, Pennsylvania.  It was collected on November 11, 1940 by Ellen Mason on "railroad property" in Thornburg, just west of the city of Pittsburgh. 

Can American bittersweet be found in Allegheny county?  It has largely been taken over by the invasive Oriental bittersweet from East Asia. The main differences between the two species are leaf shape (invasive species has more rounded leaves, native species are more elongated) and fruit (invasive species has fruit all along base of many leaves, whereas the native species has clusters of fruit at the end of each branch, as seen in this specimen).  

Oriental bittersweet (Celastrus orbiculatus) really didn't become prevalent in our area until a few decades ago.  But it sure it prevalent now.  It is also said to hybridize with the native American bittersweet, probably further swamping out the native.

American bittersweet has beautiful orange/red fruits that hang on into fall/winter long after their leaves have dropped.

Keep a look out for American bittersweet.

Well, that’s kinda weird!
These red maple (Acer rubrum) leaves were collected by Dorothy Pearth on November 6,  1959 at  Coles Summit in Huntingdon county, Pennsylvania. Dorothy Pearth (1914-1996) was a curator at the Carnegie Museum. She made two special notes on the label: “with exceptionally long petioles” and “many leaves with very long petioles.” (Petioles are the stalks that connects leaf to stem)
 
Herbarium data are often considered “biased.” All data collected haphazardly or by many different people across centuries with different intended purposes undoubtedly skew reality to some extent, depending on the research question.  It is rightfully something to consider when using specimens in research. Taxonomic bias (what species are collected), geographic bias (where specimens are collected – more often near roads, for example), temporal bias (high collection effort in some years), or collector bias (“that guy never collects grasses”) are just a few to consider. But just because “bias” may exist doesn’t mean it can’t be accounted for or the data are somehow useless.   Far from it!
 
In fact, bias can be a great thing! We want those “odd” specimens documented because they often tell us something important and new.  Maybe that specimen flowering in fall that normally flowers in summer is a sign of climate change.  Maybe that unfamiliar species is the first record of an introduced species that may  become invasive in the region.  Maybe that specimen that resembles species X, but has really huge leaves, is a new species  unknown to science!  Many undetermined specimens (that  is, those  that are identified to species)  are collected  for that very reason.  Many new species are first realized after someone  points out  that this specimen is “weird.” 
 
A recent paper in the American Journal of Botany (Pearson & Mast, 2019) surveyed collectors and search specimen records that include “outlier terms” – in other words, additional notes on the label written by the collector to point out something unusual about the specimen.  They found that this practice of pointing out outliers is an important route to detect early changes in the Anthropocene (the age of humanity).  Unusual specimens are important sentinels, bringing our attention to critical biological changes that may otherwise be overlooked in an era of rapid biological change.
 
Find this long-petioled red maple specimen online here: midatlanticherbaria.org/portal/collections/individual/index.php?occid=12233287&clid=0
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This specimen of eastern hemlock (Tsuga canadensis) was collected by former Carnegie Museum botany curator Sue Thompson on November 3, 1984 in Somerset County.  Not only was this specimen collected in the highest point in Pennsylvania (Mt. Davis, 3,213 ft), but the species is also the official state tree of Pennsylvania.  How’s that for your state trivia!?! 
 
And this is a nice-looking specimen! Hemlock is a challenging species for the herbarium.  It is notorious for shedding all of its needles when dried.  Many specimens are just sticks with all the fallen needles shoved into an envelope.
 
Eastern hemlock (Tsuga canadensis) is a culturally and biologically important species.  A keystone dominant species found across many eastern North American forests, hemlock serves as important habitat to many birds, among other species.  Its leaves are evergreen and remarkable in casting some of the deepest shade, making the understory below it distinct.  Many species are adapted to “hemlock-hardwood forests.”  It provides food, shelter, and impacts nutrient and water cycles.  It is a late-successional tree, meaning its presence often indicates older, more intact forests.
 
Unfortunately, this species is in decline across its range, and it may become the “next American chestnut” so to speak.  Hemlock is attacked by an introduced, invasive insect – the hemlock wooly adelgid (Adelges tsugae).  The sap-sucking bug was accidentally introduced from its native East Asia, spreading to eastern hemlocks in the 1950s. First in the southern US, the impacts of the adelgid are clear in Great Smokey National Park, with hemlock stands wiped out and only the dead trunks and branches.  The insect is fairly new to western Pennsylvania, only found in our region relatively recently and not yet fully spread.  Check the undersides of hemlock needles for hemlock wooly adelgid.  If tree is infected, you’ll see their distinctive white cotton-like egg sacs.
 
As forest pests like the hemlock wooly adelgid spread and affect our forests, herbarium specimens are critical, serving as baseline data for species distributions and effects on other species through time and across sites.
 
Find this specimen online here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11739325 

“Autumn is a second spring when every leaf is a flower” – Albert Camus
 
It’s peak fall color in southwestern Pennsylvania, depending on who you ask!  This beautiful specimen of red maple (Acer rubrum) was collected on November 2, 2007 by Loree Speedy near Virgin Run Lake in Fayette county. It is unclear to me what exactly the “red” in red maple refers to specifically, or perhaps many parts of the plant (flowers, leaves, petioles).  One thing is for sure – it can have beautiful bright red foliage in the fall.  Also once called “swamp maple,” this species is widespread across eastern North America.  Due to altered effects on fire, wildlife management, climate, and other environmental changes, red maple is said to have increased in abundance over the past century.
 
Red colors can be the most striking of all fall colors…but my opinion changes!  This specimen shows great variation within the leaf, with reds and greens.  Each leaf have a certain uniqueness to them.
 
Red coloration in fall leaves results from the production of red pigments called anthocyanins. The pigments serve as a protectant, a sunscreen of sorts. You may also see young or stressed leaves turn red at other times of the year for similar reasons.  Other pigments like carotenoids (oranges) and xanthophyll (yellows) are present throughout the growing season, serving as accessory pigments for photosynthesis.  As chlorophyll breaks down and nutrients resorbed, these colors have their chance to shine.  Anthocyanins, however, are actively produced in fall.
 
Fall leaf coloration is complex, and not easy to predict. Many hues exist, even within a leaf (as shown in this specimen). Every species has different coloration. And, coloration differs within species based on a variety of factors.  Each leaf is unique and although short, fall is a great time to celebrate the beauty and science of leaves.
 
All of the red maple specimens in the mid-atlantic region from the Carnegie Museum herbarium are now imaged and available online: http://midatlanticherbaria.org/portal/collections/list.php?db=328&hasimages=1&taxa=Acer+rubrum&usethes=1&taxontype=2 

This specimen of Callery pear (Pyrus calleryana) was collected on October 11, 1979 by W.Z. Fang in Jiangsu, China. Callery pear is native to East Asia (China, Vietnam).
 
But...Callery pear can be found in the United States. It was (and is) widely planted as an ornamental landscape tree.  Along streets, in residential yards, in parking lots  - it was a prized plant for well-groomed anthropogenic landscapes. It uniformly grows in low resource conditions, explodes with many beautiful blossoms each spring, provides shade, and has a decent foliage display in the autumn. As many introduced plants go, it went from prized ornamental to an unwanted “invasive species,” spreading across the landscape and affecting the environment. It is now widely recognized invasive species in many states or closely watched as a species likely to become invasive. That said, beyond the legacy of over half a century of mass plantings across the country, it is still common planted and old and new cultivars are commercially available.  USDA estimated over $23 million in sales in the US in 2009 alone.
 
How’d Callery pear get to the US? The story behind the introduction of Callery pear is a fascinating one.  Like many of our cultivated plants, seeds were collected on special expeditions in search of plants useful to horticulture, agriculture, or just because. Pyrus calleryana was first introduced to the US in the early 1900s, though not for its attractive blossoms as you might expect. Instead, it was first introduced for its disease resistance. It was successfully used in horticulture as a root stock for European pear fruit production. At the time, European pears in the Pacific northwestern US were being hit hard, grafting to a Callery pear rootstock dramatically decreased crop losses to disease. Callery pear does not produce edible fruit.

​The tree was widely planted starting in the 1960s, when it became commercially available and promoted by the nursery industry as a hardy ornamental tree.  Before that, it was planted by the US Department of Agriculture (USDA) for testing at Plant Introduction Stations in Corvallis, Oregon, and Glenn Dale, Maryland. One of these Maryland planted trees was targeted for its special traits and became the source of the hugely popular ‘Bradford’ cultivar (“Bradford pear”). In 1952, one tree was used to graft to rootstock, a plant propagation method making all plants genetically identical.  Other cultivars have since been commercialized, but ‘Bradford’ were/are exceptionally popular. Though intended to be sterile (non-reproducing), it turned out the trees were capable of setting viable seed.   The cultivars themselves are not invasive, but because multiple cultivars exist, together they can cross-pollinate to become invasive.

Herbarium specimens have been critical to understanding the spread of this species.  In a 2005 study, Dr. Michael Vincent (Miami University in Ohio) found that 50% all specimens examined over the range of 39 years were collected between 2000-2003.  Though some specimens  were collected in the 1960s in natural areas, it became widely “escaped” from cultivation in many natural  areas in the 1990s.
 
You may have noticed that most of our specimen images to date are those collected in Pennsylvania and surrounding states.  That’s because these specimens are being digitized as part of a multi-institutional project, the Mid-Atlantic Megalopolis Project, with the overarching goal to mobilize herbarium specimens across the region  to understand the effects of urbanization on plant life.  However, this project is a step towards digitizing the entire Carnegie Museum Herbarium.  The herbarium is worldwide in scope, and specimens in the Mid-Atlantic region accounting for only 35% of the 540,000 specimens.
 
As more specimens become digitized as part of the Mid-Atlantic Megalopolis Project, we’ll have a more complete understanding of the introduction and spread of Callery pear in the region.
 
Herbarium specimens are collected in the native range too! We’ll be able to compare specimens collected in the invaded range to those in its native China. The use of cultivated specimens and those collected in the native range are underutilized  but can provide critical information.

Escaped from cultivation. This specimen  (above) from Muhlenberg College Herbarium (MCA) was collected along the roadway in Montgomery county, Pennsylvania by Bayard Long in 1962. This specimen is probably the earliest specimen collected in the wild in Pennsylvania.

Many more specimens like this will be brought to light through the Mid-Atlantic Megalopolis Project.
 
Read more about this species introduction history in the popular press, published in the Washington Post  last year, and in an excellent overview by Dr. Theresa Culley (University of Cinncinati) in Arnoldia and another in BioScience.
 
See all the Pyrus calleryana specimens being made available online from the Mid-Atlantic Megalopolis project here: http://midatlanticherbaria.org/portal/collections/list.php?db=277%2C328%2C334%2C329%2C333%2C320%2C330%2C40%2C410%2C316%2C335%2C331%2C332%3B11&includecult=1&taxa=Pyrus+calleryana&usethes=1&taxontype=2
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​"There’s a tree that grows in Brooklyn. Some people call it the Tree of Heaven. No matter where its seed falls, it makes a tree which struggles to reach the sky. It grows in boarded up lots and out of neglected rubbish heaps. It grows up out of cellar gratings. It is the only tree that grows out of cement. It grows lushly...survives without sun, water, and seemingly earth. It would be considered beautiful except that there are too many of it."
 
-from Betty Smith’s classic novel, A Tree Grows in Brooklyn (1943)
(Fact check: the species is impressively resilient but does indeed require light and water. But we’ll let it slide with an artistic license here.)
 
This specimen of tree of heaven (Ailanthus altissima) was collected on October 4, 1940 by D. Berkheimer near Klapperthal in Berks county, Pennsylvania.
 
Tree of heaven (Ailanthus altissima) is a species with a fascinating and complex cultural history.  It was once glorified as a beautiful urban street tree in the United States. It was tolerant of insects, pollution, and poor growing conditions. The earliest recorded planting in the US (via England) was at William Hamilton’s estate (currently the “Woodlands Cemetery”) in Philadelphia around 1784.  It was also in Bartram’s famous garden nearby. It became popular in the plant nursery industry after 1820. But that feeling stay long, and within decades it was vilified as an unwanted weed – it had an unpleasant smell, produced prolific seeds, and resprouted from suckers causing it to spread.  Today, it is a common urban “weed” found in urban and non-urban areas across the eastern US.  It is considered invasive in Pennsylvania (and many other states). It is also considered invasive in many parts of Europe.
 
But where’s it from? Ailanthus altissima is native to East Asia, including China, Taiwan, and Korea. It has a deep ethnobotanical history in China, where it has been used in various ways in traditional Chinese medicine, with written records of its use dating to 732 AD! It also has deep roots in Chinese literature and culture. Among other uses, it has also been used in silk production, as it is a food host to a silkworm.
 
The oldest herbarium specimen from the Eastern US is undated by inferred to date from 1815-1831 from Philadelphia.  It is in the herbarium of the Academy of Natural Sciences of Drexel University (PH).  The second oldest Pennsylvania specimen is dated 1841, also from Philadelphia. midatlanticherbaria.org/portal/collections/individual/index.php?occid=6447582&clid=0
 
It is around this time of year that the abundance of Tree of Heaven in the Pittsburgh area becomes especially obvious, especially along roadsides. With large, compound leaves and found in disturbed, “weedy” areas, Ailanthus can be easily confused with the similar looking native tree, staghorn sumac (Rhus typhina). Staghorn sumac is in a different plant family (poison ivy family, Anacardiaceae), but this confusion goes way back. Linnaeus even described the species as in the same genus as sumac, so don’t feel too bad if you make the same mistake! (Side note – the taxonomic history of the species is also intense. It has been given many different scientific names over the past three centuries, with three people independently naming it at around mid-1700s!) The leaves are noticeably different upon closer inspection. The fruits are even more  clearly different. Ailanthus has brown clusters of winged seeds (called samaras, like that of maple trees’ “helicopter” seeds). These seeds can be clearly seen now on trees as their leaves drop along most highways around Pittsburgh.

Given its introduction history in the Mid-Atlantic and affinity for urban areas, the Mid-Atlantic Megalopolis Project (mamdigitization.org) will be important and fascinating to understanding more about this plant. The Mid-Atlantic Megalopolis Project is a specimen digitation effort involving more than 12 herbaria (including Carnegie Museum herbarium) funded by a National Science Foundation grant to database (put in computer), image (high res. pictures), and georeference (put on map) all specimens in the region. The region is significant because it is one the oldest, densely populated urban corridors in the US, from New York City to Washington, D.C. The Mid-Atlantic Megalopolis Project is producing a critical dataset to look at the introduction history and invasive success (and failure) of species in urban and non-urban areas across this connected region – including Tree of Heaven and many other species. 
  
This specimen image (and many other Tree of Heaven specimens in the region) are available online: http://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Ailanthus+altissima&usethes=1&taxontype=2
 
The earliest specimen in the southwestern PA at the museum was collected in 1881 in Beaver county.   

For more on the species’ fascinating history and biology in our region, check out this detailed study by Dr. Matt Kasson and colleagues done at Penn State published in 2013 in Northeastern Naturalist.