Collected on this day...
a weekly blog featuring specimens in the Carnegie Museum's herbarium.
each specimen has an important scientific and cultural story to tell.
each specimen has an important scientific and cultural story to tell.
Herbarium specimens can provide insight into plant-insect interactions. For instance, many specimens show obvious signs of insect damage to the leaves or flowers. Many other specimens, upon closer inspection under magnification, show damage that is much subtler. Sometimes, even the larvae or insects were also pressed with the plant! Some of this damage may have happened from pests in the herbarium that occurred over decades of storage. Damage from herbarium pests is a serious concern and collection managers are also conservators of these archives, keeping a vigilant eye out for damage from the elements (such as light, temperature, humidity, water, and other chemicals) and introduced pests (such as mold and insects). However, damage that occurs in the herbarium is minimized for long term preservation and luckily, insect damage that occurs in the herbarium is often easily distinguished from herbivory that happened in the wild, before the plant was collected, dried, pressed, and added to the collection.
Few studies to date have used the herbarium record to understand the ecology and evolution of plant-insect interactions. However, there are several pioneering studies at the frontier of this novel use of these collections.
This specimen pictured above of wild parsnip (Pastinaca sativa) was collected by Leroy Henry on July 17, 1968 along the Pennsylvania Turnpike not far from Pittsburgh. Leroy Henry was an influential Curator of Botany at the Carnegie Museum from 1937-1973, having collected thousands of specimens in the herbarium.
In addition to the “standard” herbarium label that gives information on what the specimen was first identified as, where it was collected, who collected it, etc., check out another typed label affixed to this sheet. This annotation label indicates two seeds were removed from for chemical analysis in 2005. Annotation labels are commonly added to specimens years to centuries later to note its use in a study, a new identification, and/or part of the specimen was removed.
This specimen was one of many specimens included in a study on wild parsnip by Zangerl and Berenbaum published in 2005 in the high-profile journal Proceedings of the National Academy of Sciences (PNAS).
Wild parsnip (Pastinaca sativa) was introduced to the United States from Europe centuries ago and has since spread to become invasive. The species is a member of the carrot family (Apiaceae). Like many other species in this plant family, wild parsnip produce phototoxic chemicals called furanocoumarins, which protect the plant from insect herbivory. These compounds also cause major skin irritations in humans, reacting with sunlight to cause nasty rashes. This group of chemicals is of the same fame of giant hogweed, poison hemlock, and other well-known toxic plants in the United States.
Zangerl and Berenbaum (2005) analyzed herbarium specimens collected over the past 150+ years. These specimens were collected from before wild parsnip was widespread in the US and compared those to specimens collected more recently, after the species was widely established. A major herbivore, the parsnip webworm (Depressaria pastinacella) was also accidentally introduced in the mid-late 1800s. The authors found that as rates of webworm attack increased, so did the toxicity of wild parsnip. Specimens from 1850-1889 (early stages of introduction) had lower levels of the toxic furanocoumarins than plants collected more recently, as well as than specimens collected in their native range (Europe), where the parsnip webworm is also native.
There is so much known and unrealized potential in herbarium specimens. This particular specimen was not collected with the intention of studying the ecology and evolution of plant-insect interactions. This study helped inform our current and future use of biological control agents to manage introduced species.
These unanticipated uses (often decades to over a century after a specimen was collected!) illustrate the incredible power of natural history collections.
See an excellent paper by Meineke et al. just published on this topic (including quantifying the effects of climate change on plant herbivory through herbarium specimens): https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecm.1307.
Check out the cool parsnip webworm study here: http://www.pnas.org/content/102/43/15529
Wild parsnip (Pastinaca sativa) in an unmowed roadside median next to Bloomfield Bridge, Pittsburgh PA on June 29, 2018.
“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.
Did you know that one of the earliest Presidents of the United States lived in southwestern PA? The American soldier and politician Arthur St. Clair, who lived in the Ligonier Valley near Latrobe, Pennsylvania, was President two years before George Washington was! Well, sort of. The US Constitution wasn’t drafted until the 1787, over ten years after Independence Day 1776. Before that, under the Articles of Confederation, there was a Confederation Congress. Arthur St. Clair was elected President of the Continental Congress in 1787.
These patriotic specimens of American Bugbane (Actaea podocarpa, formerly Cimicifuga americana) were collected on July 9, 1999 in the Loyalhanna Gorge (Rt. 30 aka the Lincoln Highway runs through it between Greensburg and Ligonier, PA), near where Arthur St. Clair owned property and lived the later years of his life (now known as Saint Clair Hollow). In the buttercup family (Ranunculaceae), American bugbane, also called mountain bugbane, is a forest understory herb similar in appearance to the more common black cohosh (Actaea racemosa). The species is currently listed as threatened in Pennsylvania.
Arthur St. Clair was born in Scotland in 1737 and fought with British troops in the American colonies during the French and Indian War. After the war, he settled in Ligonier Valley and was the largest landowner in Westmoreland County at the time. He was later a American colonel in the Revolutionary War. After America gained its independence, he was elected a delegate to the new Confederation Congress (governing body under the Articles of Confederation that pre-dates the Constitution). He served a one-year term as President of the Continental Congress in 1787, during which time the Northwest Territory was created. He later became governor of the Northwest Territory (large area which are now Midwest states). After retiring, he returned to live out his days in the Loyalhanna Gorge (between present day Ligonier and Greensburg, not far from Idlewild Park). He died in poverty in 1818.
Many towns in Pennsylvania and the Midwest are named after Arthur St. Clair, including Upper St. Clair near Pittsburgh.
A lot of history in Western Pennsylvania!
Happy 4th of July!
Although often overlooked, herbarium specimens that were collected in cultivation have important uses. These plants were intentionally planted by humans rather than growing naturally in the wild. These specimens were collected from farms, gardens, greenhouses, or even those planted in your yard or city parks. These plant species are often economically important, providing benefits to humans in the form of food, medicine, fibers, or simply beauty. The Carnegie Museum Herbarium has about 5,736 specimens that are known to be collected in cultivation, dating back to 1817!
This wheat (Triticum aestivum) specimen was collected on June 29, 1916 from a farm in Vallonia, Pennsylvania (Crawford County). This specimen was collected well before the so-called “Green Revolution” of the 1930s-1960s when agriculture changed globally with new plant breeding technologies (high yielding crop varieties), increased pesticide use, and synthetic fertilizer production and use.
Compare this particular wheat specimen (which barely fits on the herbarium sheet; note it is bent 3x to fit) to a much shorter one now on display in the We Are Nature: Living in the Anthropocene exhibit at the Carnegie Museum of Natural History. The specimen on display was collected nearly a 100 years later and is a dwarf variety. This wheat cultivar was developed through plant breeding technologies in the mid-20th century to improve crop yields. Semi-dwarf wheat was developed in Mexico in the 40s and 50s through plant breeding efforts led by Norman Borlaug, who later won the Nobel Peace Prize for his work that addressed world hunger through agricultural technologies. The majority of the world's wheat crop is now a semi-dwarf variety.
Herbarium specimens collected in cultivation could provide important information on the types, traits, and genetics of crops grown over the past two centuries, a period of much change. Are some disease-resistant genotypes or cultivars which no longer exist stored in herbaria?
Another important, yet largely untapped, source of information in these specimens collected in cultivation is the non-native species planted intentionally for ornamental purposes. Many of our non-native species which are now invasive and causing economic and ecological harm were first introduced intentionally for ornamental purposes. In many cases, information on some of the earliest introductions may be stored in herbaria. These specimens are ripe for study.
Take oriental bittersweet (Celastrus orbiculatus) as an example. Oriental bittersweet is a woody vine from East Asia, now a problematic invasive plant found throughout the Pittsburgh region and beyond. It became particularly abundant in our region in the 1980s, now common to forests and roadside woods. Interestingly, the oldest specimens collected in Allegheny County are not from the wild, but instead grown in cultivation in gardens. Two specimens grown near Highland Park collected in 1916, followed by another specimen collected 34 years later (also in cultivation!). It was not collected outside of a cultivated setting in the county until 1979. And now, it is ubiquitous! What insight can those first specimens collected in cultivation in 1916 tell us? Were these the source of introduction? And more importantly, can they provide information on basic invasion processes to help us prevent future invasions by other species?
Specimens collected in cultivation may be seen as “not natural” or otherwise less important than those collected in natural areas or found spontaneously growing without direct human intervention. But it is clear that specimens collected from cultivation have an important role to play. We must continue to record and archive cultivated species in natural history collections. After all, human impact and the blurring of “nature” and “human-made” is the hallmark of the current era, the Anthropocene, so cultivated species document nature just the same way as “wild” occurring plants.
The French naturalist Michele Adanson is said to have called the baobab as “the most useful tree.” This particular specimen pictured above was collected on June 27, 2001 by E. Mboya and others in Tanzania. The baobab is an incredible important tree to the people and wildlife of Africa. The tree can live up to a thousand years old! Baobab produces a hard fruit with white pulp that has long been a traditional food by native Africans, as well as a source for water, medicine, and shelter. For these reasons, it is also known as “the tree of life.”
The species (Adansonia digitata) was named by Linnaeus in honor of Michele Adanson, who studied specimens of this species in the 1700s. The second part of the scientific name ("digitata") refers to the 5 finger-like leaflets that make up the compound leaf. Interestingly, the Carnegie Museum herbarium includes 20 specimens collected by Adanson himself, dating back to 1753.
The baobab (Adansonia digitata) is prominently featured in the Hall of African Wildlife at the Carnegie Museum. The species biological and cultural presence in some part of Africa is unmistakable.
Below: Another baobab specimen collected in 1973 that shows the large, white flowers, which are primarily pollinated by bats.
Herbarium specimens provide key insights into the Anthropocene. In many cases, natural history collections are the only baseline we have to understand the widespread, complex effects of human activities on the earth systems over the past century.
This grass species shown here is of particular interest. This specimen was collected in Cambridge, England on June 18, 1829. This grass species (Alopecurus myosuroides), commonly known as “slender meadow foxtail” or “black-grass,” is a major weed in farm fields (especially wheat and barley), and can significantly reduce crop yields.
Unwanted plants (“weeds”) have been an ongoing fight for humans since the dawn of agriculture. The “Green Revolution” (1930s-1960s) was a point in human history when agricultural production increased at an enormous rate and at unprecedented scale, aided by technological developments in crop breeding, pesticides, herbicides, and fertilizers. It has been one time point suggested to mark the "official" start of the Anthropocene, a proposed geological era defined by human activities.
Herbicides are commonly used to control weeds to increase crop yields. With the increase of herbicides, some plant species have evolved resistance to these herbicides. In a cool study in PLoS ONE in 2013, Délye et al. did a DNA analysis of herbarium specimens collected from 1788 to 1975 to show that some individuals of this grass species already possessed the gene mutations associated with herbicide resistance well before herbicides were widely used! They show that the use of herbicides selected for these individuals, such that those individuals with herbicide resistance are now more abundant.
Who would have thought these specimens would be used this way? There are so many known and yet to be known uses of herbaria.
The collector of this specimen back in 1829 certainly didn’t think it could be used to understand the evolution and effects of herbicide use over 175 years later!
This should wake you up! This specimen of coffee (Coffea arabica) was collected on June 1847 in Jamaica by Jacob Wolle. Coffea arabica, the source of Arabica beans, is the main species of coffee consumed by humans, and is cultivated worldwide. The coffee “bean” is the seed – the hard pit inside the coffee fruit.
Why does the Carnegie Museum have coffee specimens from Jamaica from the 1840s, you might ask? Surprisingly, some of the oldest specimens in the Carnegie Museum herbarium were collected in Jamaica! Jacob Wolle was the grandfather of William Holland, one of the first directors of the Carnegie Museum (from 1901-1922). Holland himself was born in Jamaica, where his father was a Moravian missionary. The CM herbarium has 2,514 specimens from Wolle’s collection, dating as far back as 1819!
The coffee specimen below, also from Jamaica, was collected by former Carnegie Museum director William Holland's father, Francis R. Holland in 1844.
This post was inspired by a group of artists from Vietnam whose art is inspired by coffee and coffee plantations. They stopped by the herbarium earlier this year for inspiration.
Plants are an important part of the urban landscape – both those planted species and those that are wild. There are more to “weeds” than you might think. From sidewalk cracks downtown to city parks, plants are important to the ecological, economic, and human health of our city. Understanding what plants thrive (or not) and their roles in a healthy, functional ecosystem in cities and human dominated environments that define the Anthropocene. With a recent award from the National Science Foundation (starting this September and running for 3 years ), we will be digitizing all specimens in the Carnegie Museum’s herbarium from the Mid-Atlantic Region (PA, MD, NY, NJ, DE & Washington, DC). That is a total of nearly 190,000 specimens! We are partnering with an ongoing herbarium digitization initiative, the Mid-Atlantic Megalopolis Project, which includes 11 other institutions in an effort to document and understand the past, present, and future plants in urban environments.
This specimen of Bellis perennis, also called “lawn daisy,” was collected just outside the museum in front of the Carnegie Library by former botany curator Otto Jennings on May 26, 1909. This member of the sunflower family (Asteraceae) is native to Europe but has since been transported across the world and has become naturalized in many areas, joining the urban flora.
This project will facilitate a better understanding of the often-overlooked biodiversity in the city and the plants that make up Pittsburgh, both today and 150+ years ago.
Expect more posts in the coming months that highlight the Plants of Pittsburgh!
It is that time of year in Southwestern Pennsylvania.
Kennywood and Idlewild are open!
Although they’ve changed ownership over the past 100+ years of operation, both amusement parks have similar origins and remain favorite recreation spots for many across western PA and beyond.
Located in Ligonier, PA in the heart of the beautiful Laurel Highlands, Idlewild goes back to May 1, 1878 when land owner William Darlington gave rights to Judge Thomas Mellon to use the grounds for picnic and pleasure. Judge Mellon owned the Ligonier Valley Railroad, and Idlewild was started as picnic park to attract people to the Ligonier Valley Railroad. Darlington gave Mellon the permission “Without compensation in the shape of rent for three years from the first of April 1878 provided no timber or other trees are to be cut or injured – the underbrush you may clear out if you wish to do so.” The park was an immediate hit, with the “tops of the [train] coaches were covered with boys.” You can still see the Idlewild train station in the park today. You can also visit the Ligonier Valley Railroad Museum to learn more about the history of the region and the Ligonier Valley Railroad at the recently restored Darlington Station in nearby Darlington.
Collected in late May, 1923, the specimen below was found by in by E.H. McClelland at Idlewild Park, near Ligonier, PA. This herbarium sheet actually contains two different phlox species, Phlox stolonifera (creeping phlox) and Phlox divaricata (wild blue phlox). There are at least seven species of phlox native to Pennsylvania. Phlox is a popular choice among wildflower gardeners. Phlox can be easily confused with Dame’s rocket (Hesperis matronalis), a non-native plant in the mustard family common along many wooded streams and roadsides. An easy way to tell the difference is by the flowers: wild phlox have 5 petals while Dame’s rocket has 4 petals. Dame’s rocket is in the mustard family, whose flower petals characteristically form an “+” or cross (hence its former family name Cruciferae; family now called Brassicaceae). Take the Idlewild train through the woods and see if you can spot these species now, 95 years later.
Located in West Mifflin, PA near Pittsburgh, PA, Kennywood has strikingly similar origins. It opened as a “trolley park” in May 1899 as an attraction at the end of the Monongahela Street Railway (also owned by the Mellon family). It was long known as a popular picnic spot, even before the park’s opening.
The specimen below of Trillium erectum was collected in May 1903 in Kennywood (4 years after the park opened!). This beautiful spring flowering forest understory plant is commonly known as “Wake robin,” “red trillium,” or even “stinking Benjamin” (the flowers have a bit of a wet dog scent). Trillium is done flowering in southwestern PA now but can still be seen, but with withered or no petals.
Today is the famous botanist Carl Linnaeus' birthday, born on May 23, 1707. Linnaeus was hugely influential in taxonomy and nomenclature, having named and described many species.
This specimen of Fritilaria meleagris was collected in Linnaeus' home country of Sweden, in 1894, 187 years to the day after he was born. Not surprisingly, this species was named by Linnaeus, and included in his classic publication, Species Plantarum (1753). Many formal scientific names are followed by "L." denoting Linnaeus as the authority attributed to naming the species.