Mason Heberling

Not all bittersweet vines are invasive to Pennsylvania. This specimen was collected on June 14, 1965 by botany curator Leroy  Henry  in Clearfield county,  along  Rt 969. American bittersweet (Celastrus scandens) is a woody vine that  blooms in June, which turn to beautiful clusters of orange/red fruit in late summer/fall.  The species is native to eastern USA, found along open thickets/edge of woods.

American bittersweet (Celastrus scandens) might be easily  confused with the much more common Asian bittersweet (Celastrus orbiculatus).  There are two major visual  differences between the species: 1) flower/fruit --  native species has single terminal cluster of many flowers/fruits at tips of branches, whereas the invasive has flowers/fruits at axils of leaves (where leaves connect to stem; and 2) leaves -- native  species' leaves are more elongate, whereas the invasive species' leaves are more round, often even circular ('orbiculate').

American  bittersweet is no longer common in Pennsylvania, most likely taken over by the closely  related Asian bittersweet.   Asian bittersweet  is a relatively newer addition to the  flora of Pennsylvania, not showing  up  in  western PA and  the  Pittsburgh region until  the 1980s.  Given its abundance and distribution throughout the region  now,  it is hard to fathom it was not present only several decades ago.

Research over the past decade has shown that the invasive species hybridizes with the native, likely contributing to  the decline  of the native American bittersweet.

Keep a look out for American bittersweet in our region.  (I have  not  seen it in Allegheny county, although we have historic  records)

This specimen image is now publicly available online:
http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12131436&clid=0

This is a special specimen.  The Carnegie Museum herbarium is full of specimens of scientific and historical importance.  And this is a notable one, collected in June 1830 by William Darlington in West Chester, Pennsylvania.  William Darlington (1782-1863) was an important figure in the history of Pennsylvania botany. Darlington was a physician, politician (US House of Representatives 1815-1823),  and as  you might guess – a botanist!  At the University of Pennsylvania, Darlington studied botany under Benjamin Smith Barton, a well-known botanist who also trained Meriwether Lewis (of the Lewis & Clark Expedition). Darlington wrote several He spent most of his life in West Chester, PA. He wrote some of the earliest botanical works, including a flora of Chester County in 1826 and others on agriculture.  Many of his specimens are among the earliest documentation of Pennsylvania’s flora and are preserved in the William Darlington herbarium at West Chester University.
 
This particular specimen is of the native shrub Euonymus americanus, commonly called “strawberry  bush.”  Despite the name, it is not related to strawberries, but in the bittersweet/spindle family, Celastraceae.  You may recognize some similarities with the related species from East Asia, burning bush  (Euonymus alatus), which is commonly planted for its bright red fall color (around Cathedral of Learning in Pittsburgh, and many other places).  However, burning bush should not be planted, as it is invasive, spreading into natural areas.
 
In the Carnegie Museum herbarium, there are 62 specimens collected by Darlington between 1828 and 1840, mostly from Chester County, PA. 
 
How’d some of Darlington’s specimens end up at the Carnegie Museum?  This specimen was part of Jacob Wolle’s personal collection, who was the grandfather of William Holland, the first director of the museum.
 
This specimen image is now publicly available online: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12131484&clid=0
 
Read more about  Darlington and other influential figures in the history of Pennsylvania botany at Herbarium World: https://herbariumworld.wordpress.com/2017/07/10/william-darlington-and-the-pennsylvanica-botanical-circle/

Even though it was collected in Japan, this specimen might look familiar in Pennsylvania. This specimen of wintercreeper (Euonymus fortunei) was collected by M. Togashi in Japan in 1985. Native to East Asia, wintercreeper (also called Fortune’s spindle or climbing euonymus) was introduced to North America in 1907 for use as a ground cover.  In fact, it can be found just outside the Carnegie Museum, around the parking garage.  It can escape cultivation, to establish and become naturalized (sometimes invasive) in the Eastern United States.  Wintercreeper is a fast-growing woody vine which has evergreen leaves.  Wintercreeper is recognized as invasive by the Pennsylvania Department of Conservation and Natural Resources (PA DCNR), with potential to cause ecological harm in natural areas (link).
 
Herbarium specimens are valuable resources to study invasive species -- not only to monitor changes through time (since introduction) and to track its spread across the US, but also to compare to populations growing in the native range.  Much untapped potential in herbaria worldwide for understanding species invasions.

Stumbled upon this neat little book from 100 years ago in the Botany library, which promotes the use of this plant as an ornamental.  The book was published in 1917, ten years after wintercreeper was introduced to the US.  Many states (including PA) now recognize this species as problematic or having the potential to become invasive.  [note: Evonymus radicans is a synonym for Euonymus fortunei var. radicans]

Below: Euonymus this morning outside the museum.  Probably not much photosynthesis happening this winter morning, given it is 0 °F (feels like -18°F​)!

Collected on this day in 1935, this eastern wahoo (Euonymus atropurpureus) specimen was found near Connellsville Pennsylvania by John Franklin Lewis.
Eastern wahoo is native to midwestern states and parts of Pennsylvania.