HEBERLING LAB

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
 

Fall blooms rival those of spring
 
In the northeastern United States, we often think of spring as a time for wildflowers.  But the fall is, too.  
 
It is easy to be distracted by the beautiful fall foliage, when our landscape turns brilliant shades of red, orange, and yellow.  But when many plants are shutting down for the winter, others are just kicking into gear.
 
Many wildflower species bloom well into fall, both in open areas and in the forest understory.  One group of plants are the fall blooming “asters.”  In same plant family as sunflowers and dandelions (Asteraceae), Aster was once a very large plant genus in our native North American flora (somewhere along the lines of >175 species!), but as we learned more about the evolutionary relationships of these plants, they have since been split into multiple genera (plural of genus). In fact, there is only one “true” Aster in Pennsylvania, Tatarian aster (Aster tataricus), which is actually not even native to Pennsylvania!  Regardless of the scientific name, these plants are commonly referred to as asters.  And they put on quite an autumn show in Pennsylvania.
 
Perhaps one of the most common woodland asters in Pennsylvania is white wood aster (Eurybia divaricata, formerly known as Aster divaricatus).  This specimen was collected in September 29, 1967 by N.R. Farnsworth in Pittsburgh’s Schenley Park.  This species can still be found in Schenley Park, and many parks, woodlands, and wooded roadsides across Eastern North America.
 
Fall foliage is beautiful in Pennsylvania.  But don’t forget to look down at the flowers, too!
 
Find this white wood aster specimen here: https://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11826562

Check out the “santa claus” pappus on this specimen of bull thistle (Cirsium vulgare), collected on July 26, 1966 by Leroy Henry near Woodbine (Butler county), Pennsylvania.  Leroy Henry was a botany curator at the Carnegie Museum.  All species in the genus Cirsium are known as “thistles.”  They have distinctive spiny leaves and stems, with even more distinctive purple flower heads. There are native thistles, but many are introduced, common in disturbed areas and in and around agricultural fields across the country.  Bull thistle is native in Europe and Western Asia, but widely introduced across the world, including North America.  It is considered invasive in many areas.  It is the national flower of Scotland.
 
Keep an eye out for thistles, and “santa clauses.”  Don’t forget to make a wish.
 
Find this bull thistle specimens here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11831581&clid=0
​

This hawkweed specimen was collected on March 16,  1952 in Argentina by Hermann Otto Sleumer, a Dutch botanist who lived from 1906-1993 who published over 1,422  plant names, describing these species new to science!
 
And this species was one of them: Hieracium eriadenium Sleumer.  The scientific binomial name is in italics  (genus species) followed by the botanical authority (here, “Sleumer”).   This denotes that Sleumer published the description of the species.
 
In fact, Sleumer actually cited this specimen in the publication four years  after  it was collected (1956), thereby making this specimen a “type” specimen.  Type specimens are of special scientific importance, as they are designated specifically to define the species. 
 
Herbarium hairs
 
Hawkweeds (in the genus Hieracium) are in the sunflower/composite family (Asteraceae). As can be seen in this specimen, these species tend to be especially hairy.  Some species are introduced outside of their natural range and considered invasive and  actively spreading.
 
One study used digitized specimens of Hieracium to measure the effects of UV-B (ultraviolet-B) radiation on the density of hairs and length of hairs across native and  introduced  ranges  (Northern and  Southern hemispheres).  The found longer leaf hairs and more dense hairs correlated to higher UV-B. Leaf hairs were longer in their introduced range (Southern hemisphere).  This study was possible because of digitized specimen images.  Find this 2017 study here: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0175671 
 
Find this specimen and more here: http://midatlanticherbaria.org/portal/collections/list.php?db=all&catnum=CM107943&othercatnum=1

nUnnamed, but not forgotten!
 
Today, we celebrate the 9th birthday of this specimen...that was collected 36 years ago.
 
This specimen was collected on leap day, February 29, 1984 in Brazil by Keiichi Mizoguchi.
 
Fun fact: The Carnegie Museum herbarium includes 85 specimens collected on leap day, collected between 1872 until 1990.  That’s a lot of leap years!
 
Aside from it being collected on leap day, the specimen label might seem even more unique.  Where most herbarium specimen labels have the species name, this one is blank. A big blank spot. The collector did not identify this specimen, nor has anyone else in the past 36 years (yet).  This is an “indetermined” or unidentified specimen.  It is filed in the sunflower family (Asteraceae) based on its flowers, but it is otherwise not identified.
 
We can’t forget about these unidentified specimens.  Especially those collected on leap day!
 
Specimens in the herbarium are arranged by plant family, then genus, then geography (where it was collected), and in nearly every genus, at the bottom of all these folders is a black colored folder labelled “undetermined” (also called “indet.”) that includes those specimens that have not yet been identified to species.  Of the over 525,000 specimens in the Carnegie Museum herbarium, about 2% (= 10,588 specimens), are not (yet) identified to species.
 
This specimen is most likely a member of a species already known to science, but an expert has not yet identified this particular specimen yet.  However, many undetermined specimens may be undescribed (that is, new to science!).  The name and description of new species (alpha taxonomy) is a major purpose of herbaria.  A study in 2010 estimated that of the estimated 70,0000 species yet to be described, over HALF are lying in herbaria right now!  They also found that only 16% of new species descriptions were done within 5 years of specimen collection, and 25% of new species descriptions involved specimens that were more than 50 years old!
Study abstract here: http://www.pnas.org/content/107/51/22169.abstract
 
Taxonomy (branch of science on classification of organisms) is always changing.  Species names are changed, what was once thought to be one plant species or family is split into many, and what was thought to several species is lumped into one.  And with further information or upon review by experts in particular plant groups. specimens are determined to be a different species than what the original collector called it.  Annotation labels are added to specimens all the time – these labels revise the species listed on the original label.  A typical annotation label includes the revised species name and details, the name of the person making the annotation, and the date.
 
Some specimens can have many annotations, which nicely demonstrates the community culture of science as a process with constant revision as we learn more about the world around us.
 
Find this specimen here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=12339031&clid=0

Check back, maybe it'll have a species name on it by next leap year!

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.