HEBERLING LAB

Though the supercontinent Pangea broke apart many millions of years ago, the Anthropocene is marked by a new kind of Pangea. Though the seven continents as they are today may not be physically connected into a single landmass, they are perhaps more connected than they have ever been. The globalization of human activities has brought species from around the world into contact which otherwise would never interact. Some species are intentionally moved from one continent to another, such as the plants in gardens, while other introductions are accidental, mere unintentional passengers of human increasingly global activities. Introduced species can fundamentally alter the landscape and are regarded as one of the top threats to native biodiversity.
 
Invasive species are those introduced species which are non-native and spread without human intervention.  Many invasive species alter ecosystem functioning and change regional biodiversity. Invasive plant species have become a common part of our landscape. Some were brought over hundreds of years ago by European colonists. Others have arrived much more recently.
 
In Pennsylvania, the invasion of some plant species are obvious – that is, a unique species arrives, thrives, and become abundant. These invasive species have no record of being in the area and can spread rapidly, sometimes over the course of a human lifetime or shorter. Many invasive species are still actively spreading across the landscape. For instance, garlic mustard (Alliaria petiolata) is a well-known forest herb from Europe introduced to North America in the mid-1800s and after more than a century are now common across Pennsylvania forest. Another obvious example is giant knotweed (Reynoutria sachalinensis), a native to parts of East Asia, first recorded in western Pennsylvania in the 1920s and has since spread to line many of Pennsylvania’s rivers and streams today. You can’t go far in the Pittsburgh region without seeing invasive knotweed.
 
Other species invasions are less obvious. These so called “cryptic invasions” are the introductions of very closely related species or subspecies which originated elsewhere.
 
This specimen of common reed (Phragmites australis) tells the tale of a widespread cryptic invasion. The specimen was collected by Carnegie Museum botany curator Otto Jennings on November 2, 1930 along the shores of Lake Erie at Presque Isle, Pennsylvania. Common reed is a major problematic invasive species, crowding out native species in this unique habitat at Presque Isle. When this specimen was collected over 90 years ago, it was not nearly as abundant as it is now.
 
But is it non-native? Common reed, or often simply called Phragmites, has a very widespread distribution, found in wetlands and shores across all continents except Antarctica. It is even not an uncommon site along wet areas near highways. It is among the most widely distributed plants in the world.
 
Reed is non-native to the United States...well, mostly. In the 1800s, botanists considers Phragmites to be a relatively uncommon plant. Evidence from fossils and paleocological research show that the species has indeed been in North America for many thousands of years. However, it didn’t start to become abundant until the early 1900s and after. Some botanists suggested the sudden success of the species could be due to human disturbance.  A pioneering herbarium-based study 2002 published in the PNAS by Dr. Kristin Saltonstall sequenced DNA from herbarium specimens collected before 1910 and recent collections to show that the spread of Phragmites in the United States was due to the introduction of a non-native strain of the species that originated from Europe.
 
Pretty cool, huh? And this finding was made possible with herbarium specimens.
 
So, is this particular specimen native or not?  I don’t actually know, but with expert examination and genetic analysis, we could find out!
 
Find this specimen and 149 more in the Carnegie Museum herbarium here: https://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Phragmites+australis&usethes=1&taxontype=2

A large stand of Phragmites at Presque Isle State Park, Pennsylvania (August 2019).

Bright fall foliage of deciduous trees gets a lot of attention in autumn...and rightfully so!  But fall is also a time when those minority of plants that don't drop their leaves also become more prominent. 

This evergreen specimen of great rhododendron (Rhododendron maximum) was collected by John A. Shafer in "Schenley Homestead" in Pittsburgh  in October 1883.  The fruits on the specimen are a reminder  of the big blooms from the summer.

This specimen was collected in Schenley Park before it was a park! Pittsburgh's second largest and much beloved city  park came to be after the donation of the large tract of woods by Mary Schenley on October 30, 1889 -- six years after this specimen was collected.

Just adjacent to the new Schenley Park, Carnegie Museum of Natural History opened its doors several years later in 1895, where this specimen would eventually end up.  Before that, the specimen was a part of the herbarium of the Botanical Society of Western PA, which would later become the Carnegie Museum herbarium.
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Botanical look-alikes...on the other side of the world!
East Asia-Eastern North America are more similar than you might think.
 
This maple specimen was collected in August 1937 by J.R. Steck and R.J. Templeton in Pittsburgh’s Schenley Park. At first look, it is clearly a maple...its leaves have that “mapley” look!  But upon closer inspection, this specimen was collected from a planting. The species is from Japan – Honshū maple or grey-budded snake-bark maple (Acer rufinerve).

Now, check out this doppelgänger specimen, another maple collected by famed Carnegie Museum curator Otto Jennings in late August 1925 in Elk County, Pennsylvania. This similar looking species is found across Eastern North American forests – striped maple (Acer pensylvanicum).  Though you can’t tell from these leaves and stems, the bark also has distinctive striping (hence the name) that is uncannily like its Asian relative species above.
 
There are many species across Eastern North America and far away East Asia that look almost identical at first glance.  Why?  This observation has long been of interest to botanists for centuries, notably by Asa Gray at Harvard in the 1800s. Eastern North America and East Asia are comprised of many shared genera across continents, with species within remarkably similar!  These are called “disjunct” genera, resulting from a shared evolutionary history, with both floras once connected in geological time but have since been separated over many thousands of years. Interestingly, of the shared genera between regions, East Asia comprised roughly two times the number of species within compared to Eastern North America.  A lot of interesting evolutionary studies have been done on this disjunction across these floras, with many more to do!
 
Find these maple specimens and 3,030 more from across the world in the Carnegie Museum Herbarium here: https://midatlanticherbaria.org/portal/collections/list.php?db=328&includecult=1&taxa=Acer&usethes=1&taxontype=2
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A flower with no leaves?
 
This leafless specimen was collected in July 1925 in Rock Run, Forbes State Forest in Rector, Pennsylvania.  This site is not far from what would only a few decades later became Powdermill Nature Reserve, the field station of Carnegie Museum of Natural History. 
 
This specimen was collected by Otto Jennings, an influential botanist and curator at Carnegie Museum.  Jennings had many roles during his 60 years at the museum (1904 until his death in 1964), including Director of Education and even Director of the museum.  He was also a university professor at the University of Pittsburgh, serving as the Head of the Department of Botany and later, the Head of the newly formed Department of Biological Sciences in 1935.  On top of that, Jennings somehow was a prolific plant collector, among the top contributors to the Carnegie Museum Herbarium with nearly 35,000 specimens and more distributed in collections across the world.
 
So, where’d the leaves go on this specimen? No, it isn’t parasitic. Wild leeks (also called ramps), Allium tricoccum, has a unique phenology, or timing, of leaf out and flowering. The species emerges very early in the spring, among the earliest in our woods. In this way, the species is a typical “spring ephemeral.” The long leaves soak up the sun before being shaded out by tree canopies a month or two later.  At that point, the leaves dies back.  However, unlike other spring ephemerals, wild leek does not flower in the spring.  Instead, months later, in July, the leafless plants send up a solitary flowering stalk.  This is quite unusual – a flower coming out of the ground in the middle of the woods, with no signs of leaves.
 
Wild leeks or ramps are in the onion family (Amaryllidaceae, formerly Alliaceae), forming bulbs with a distinctive onion flavor and ball shaped flower heads typical in the onion family. Ramps are edible, with a long history of human use by native people and European settlers. Ramp festivals are common throughout Appalachia to this day. However, the species is prone to exploitation and overharvesting, so do not harvest without permission and following sustainable practices to not affect the population.
 
The species is often treated as having two varieties: var. tricoccum (wild leek) and var. burdickii (narrow leaved wild leek). It depends who you ask, but more studies are now more clearly showing that this species may in fact be multiple species based on very distinct phenology (timing of flowers) and leaf traits (color, width).  This case highlights the importance of herbarium specimens in documenting our flora and understanding the complexities of biological diversity.
 
Also note the small label added to this particular specimen recording this specimen was used in the taxonomic treatment of the species in the Flora of North America, identified by T.D. Jacobsen who co-authored the treatment. Dr. Jacobsen is the current director of the Hunt Institute for Botanical Documentation at nearby Carnegie Mellon University.
 
Keep an eye out for those leafless flower stalks in the woods!
 
Find this ramps specimen and 174 more in the Carnegie Museum Herbarium here: https://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Allium+tricoccum&usethes=1&taxontype=2

Left: The leaves of wild leeks carpeting the forest floor in early spring.
Right: The solitary flower stalks poking through other vegetation in mid-summer.

One specimen isn’t always enough
Archiving biological variation.
 
This specimen is not a specimen but a set of five specimens!  Same species (large flowered trillium, Trillium grandiflorum). Same site (in Somerset county, PA). All collected on same date (June 4, 1982) by Frederick H. Utech and Masashi Ohara.
 
We know that one specimen of every species is not enough. Having many specimens of many species, across many sites, and through time are necessary to document what  organisms lived where, when, how far species ranges extent, and how these change through time. 
 
But why collect that many vouchers of the same species, from the same site, on same date? One reason might be to send “duplicate” vouchers to other herbaria, both to help other collections expand their holdings, to get expert opinions on identification, and/or to protect against (unlikely but very possible) damage that may happen in one herbarium (like fire, flood, insect damage – oh my!). 

But that isn’t what happened here.  All specimens are stored together at Carnegie Museum of Natural History.
 
So why? Well, it is simple, but quite genius, really. Utech and Ohara collected a “life history” voucher series.  That is, these specimens each show different stages of the species’ development from small cotyledon-bearing seedlings just germinating above ground, to one leaved plants, to small to large three leaved juvenile trilliums that have not yet flowered, to large adult plants with flowers.
 
Utech and Ohara, along with Shoichi Kawano, pioneered this method of collecting and advocated for its importance in a 1984 essay in the Journal of Phytogeography and Taxonomy. Historically, plant specimens are collected with a major specific purpose in mind – to document the plant was there at a given time. To do that, botanists of course collect specimens that are best for identification, such that others can verify the species.  For most species, that means plants tend to be collected when they are adults and reproductive (with flowers and/or fruits).  Specimens without reproductive organs (called “vegetative” specimens) are generally viewed as less useful for this purpose and often avoided.
 
But Utech and others found that this standard approach,  though useful for some research, did not cut it for their work. As organismal biologists studying the life history, ecology, and life cycle of species, they found many species were not well represented in herbarium collections.
 
Many species, like trillium, have distinct life stages from seedling to juvenile to adult. Many species form overwintering leaves or juvenile leaves that differ dramatically, even unrecognizably, from “typical” adult specimens. 
 
So there’s good reasons to collect across life history and across individuals within a population. Biological collections are all about archiving biodiversity in its many forms, whether across deep time with fossils, across species, within species, or even within populations at a specific site.
 
Dr. Utech (1943-2021) was a curator at the museum from 1976 until 1999. He was then a research botanist at the nearby Hunt Institute for Botanical Documentation until his retirement in 2011, notably contributing to 3 volumes of the Flora of North America project.  More than 23 thousand specimens in the Carnegie Museum herbarium were collected by him. Dr. Utech passed away earlier this year but his legacy lives on. You can find his obituary here: https://www.legacy.com/obituaries/triblive-tribune-review/obituary.aspx?n=frederick-h-utech&pid=197812108&fhid=9856
 
Inspired by the method of life history series and the need for new perspectives in the way we collect, CMNH Botany staff are working to promote and expand these ideas. We are presenting some of these ideas at the Society of Herbarium Curators annual meeting later this summer.
 
Find many more specimens (24,662 to be exact!) collected by Dr. Utech (including other life history series vouchers) here: https://midatlanticherbaria.org/portal/collections/list.php?db=all&collector=Utech

What are those yellow flowers?
A common roadside plant.
 
This specimen of yellow rocketcress (Barbarea vulgaris) was collected in Lower Burrell, Pennsylvania on May 28, 1993 by Fred Utech.  Utech (1943-2021) was a curator at the museum from 1976 until 1999.  More than 23 thousand specimens in the Carnegie Museum herbarium were collected by him.
 
Yellow rocketcress (or simply “yellow rocket” among many other common names) is a plant in the mustard family (Brassicaceae) with yellow flowers that bloom in mid to late spring.  Introduced from Europe/Asia/North Africa, it is now very common in Pennsylvania and many parts of North America. It is a common site along roads, especially ditches along highways.
 
Find this specimen (and 474 more!) of yellow rocket here: https://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Barbarea+vulgaris&usethes=1&taxontype=2
 

Spring at Powdermill.
An early bloomer.
 
This specimen of coltsfoot (Tussilago farfara) was collected at Powdermill Nature Reserve, the field station of Carnegie Museum of Natural History in 1957, just one year after Powdermill was established. It was collected by Leroy Henry, a curator of botany at the museum from 1937 until 1972 (though was also affiliated with museum before and after that, too!).  Henry is an important collector for our region, with >36,000 specimens in the Carnegie Museum herbarium.
 
At first look, the plant may be confused with your common dandelion.  It has definite similarities, as it is in the same plant family, Asteraceae, and with yellow flowers.  But, as you’ll notice from the specimen – it doesn’t have leaves!
 
Coltsfoot is introduced to Pennsylvania, native to Europe, and quite unique in our flora.  It blooms very early in the spring, with dandelion-like flowers poking through.  The leaves will soon follow, shaped like – well – a colt’s foot!  Quite different than dandelion. 
 
Its blooming also makes it a great species to track changes in bloom time using herbarium specimens.  The species was among the first to be use in a pioneering study published in 2006 using herbarium specimens by Claud Lavoie and Daniel Lachance.  In Southern Quebec, they found coltsfoot bloomed 15-31 days earlier in recent decades, compared to pre-1950. Earlier blooming was strongly linked to climate change in the region.  The plants also showed a clear signal of flowering earlier in the city (due to urban heat island).
 
We have plenty of spring ephemerals that bloom early, but coltsfoot doesn’t die off by summer.  The plant will keep its leaves well after it blooms, into late fall.
 
This strategy is interesting, and I can’t think of many of plants in our flora that does this.  Is it on to something?
 
Keep an eye out for coltsfoot, especially along wooded roadsides.  Once you see a big bloom, check back later in the year.  The leaves can get quite large.
 
Find this specimen and more here: https://midatlanticherbaria.org/portal/collections/list.php?db=all&catnum=CM092465&includeothercatnum=1
 

Spring is springing as we speak
in the city and beyond.
 
This specimen of common chickweed (Stellaria media) was collected on the campus of Carnegie Mellon University in Pittsburgh in a “mostly shady area.”  Though small, if you look closely you are met with a charismatic tiny flower.  Common chickweed is incredibly common across the world, found in every continent (except perhaps Antarctica?).  Like many cosmopolitan lawn weeds, it is native to “Eurasia” and its exact native range is unclear.  But it is considered not native to North America.
 
Common chickweed can be found from an urban lawn to a forest in Pennsylvania.  The plants can form a mat along the ground.  They can be found just about year round when snow isn’t on the ground, and like dandelion, flowers throughout the year.
 
But the flowers now are also telling – spring is on the way.  For some plants, such as skunk cabbage and red maple, spring has already sprung.
 
This species is a good one to look out for during the upcoming City Nature Challenge!
 
Find this specimen and more here: https://midatlanticherbaria.org/portal/collections/list.php?db=all&catnum=CM540683&includeothercatnum=1

Honeysuckles will be back soon. 
But this one never really left for the winter.
 
This specimen of winter honeysuckle (Lonicera fragrantissima) was collected in West Conshohocken, PA near the Schuylkill River outside of Philadelphia by Bayard Long.  Collected flowering in a “rubbish-dump,” no less! Bayard Long (1885-1969) was a Philadelphia-area botanist and an active member of the Philadelphia Botanical Club (founded in 1891 and still exists today).  He was a prolific collector and served as Curator of the Club’s Local Herbarium for 56 years (housed at the Academy of Natural Sciences). About 982 specimens collected by Long are preserved for the long haul in the Carnegie Museum herbarium.
 
Winter honeysuckle not only has a fun scientific name to say (“fragrantissima” rolls off the tongue) but is easy to identify among the many species in the honeysuckle genus (Lonicera in plant family Caprifoliaceae).  That is, it has almost evergreen (or in Pennsylvania, almost evergreen), thick leaves that partly persist into the winter, unlike any of the other shrub honeysuckles in Pennsylvania.  (Emphasis on shrub, because the invasive vine Japanese honeysuckle – Lonicera japonica- also has persistent leaves through much or all of winter).
 
It is also known as “sweet breath of spring” for its aromatic flowers (hence its specific epithet, fragrantissima – think Bath and Body Works scent), which appear in late winter (and in this specimen!).
 
Introduced from China as an ornamental and often planted for its foliage, this species is now invasive in many states in the US.  I must admit I don’t see it very often “escaped” outside of plantings in Western PA, but that doesn’t mean it doesn’t exist, or won’t escape in time, especially given it is problematic in other areas of the US.
 
So, you really shouldn’t plant it.  Though Pennsylvania has native honeysuckles, the most abundant and common ones are introduced, affecting native vegetation and wildlife.
 
Find this specimen (and search for more) here: https://midatlanticherbaria.org/portal/collections/list.php?db=328&catnum=CM302294&includeothercatnum=1
 

Not yet blooming here, but it likely is in the Mediterranean.
 
This specimen of lesser celandine (Ficaria verna formerly known as Ranunculus ficaria, in the buttercup family, Ranunculaceae) was collected in January 1911 by Mary F. Spencer in Corsica.  A part of France, Corsica is an island in the Mediterranean.  This specimen was collected in its native range, which extends from Europe to west Asia.
 
Lesser celandine is quite remarkable, one of the earliest blooming spring wildflowers. It isn’t blooming in the Pittsburgh region yet, but can be as early as March.  It was introduced to North America and is actively spreading throughout forest understories in Western PA and beyond, especially along streams and floodplains.
 
Lesser celandine is a problematic invasive species. And only likely to become more of a problem as it actively spreads across the landscape.  It is unique among invasive species, perhaps the only with a “spring ephemeral” ecological strategy.  Spring ephemerals produce leaves and flowers very early in the spring and dies back before the overstory trees produce leaves.  It forms dense mats along the forest floor, crowding out our native spring wildflowers.
 
It was introduced intentionally as a garden plant, producing glossy, yellow flowers which can be quite beautiful.  But it should not be planted, as it negatively impacts our forests and can easily spread outside gardens into natural areas.
 
Keep an eye out for this species in Pennsylvania!  I have been noticing it more each year. 
 
Find this lesser celandine species here:  https://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12087827
 

Lesser celandine (Ficaria verna​) invasion in Fox Chapel, Pennsylvania.  The species can form dense mats on the forest floor, emerging in early spring in a spectacular display of flowers.  But it is very invasive, crowding out native species.  As a spring ephemeral, the species takes advantage of the high light levels in the spring and completes its aboveground life cycle before being shaded out by the trees overhead.