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.
I love stumbling upon specimens collected from the same site. These two specimens of blue-eyed Mary (Collinsia verna) were collected by two different collectors on April 28th along Chartiers Creek near Pittsburgh, PA. But they were collected 74 years apart: Thomas C. Porter in 1871 and again by Carnegie Museum curator Otto Jennings in 1945. I doubt recollecting on the same calendar day, same site was intentional. Having duplicate specimens collected from the same site and from the same location decades apart makes the herbarium all the more powerful to measure biological change through time, including population size, morphology (size/shape differences) and other traits, and genetic changes.
Blue-eyed Mary (Collinsia verna) is a beautiful plant, with deep blue colored petals that give it is quirky name. It is a winter annual, meaning it germinates in the fall/early winter and blooms in the spring, produces seeds, and process repeats. It is not very common in Pennsylvania anymore and is tracked as rare in Pennsylvania. It can be found across the central and eastern United States in damp, rich woods and especially in valleys and slopes in floodplains along creeks. Seeing a population of blue-eyed Mary can be breathtaking in spring – with flowers carpeting the forest floor as far as the eye can see.
Expect more "recollected on this day" posts. Last year, we botanists initiated a long term "recollection" project at the Carnegie Museum of Natural History where we are revisiting sites across western Pennsylvania on the same calendar day as former plant collectors to compare current plants to those of our historic specimens. We are focusing on sites where collections are particularly strong -- southwestern Pennsylvania. Many of these sites are now state parks, roadsides, or have been developed as residential areas and/or have been transformed by human activities altogether.
Some results from the first year of this project can be found in the new We Are Nature: Living in the Anthropocene exhibition at the museum. These specimen recollections will grow the plant collection at the museum in a way to maximize future research. For instance, we can compare phenology (for example, flowering times) and how they might be affected from a century of climate change. We are also documenting introduced and invasive species which were absent from these sites 20, 50, or 100+ years ago, as well as native species which may no longer be locally present or abundant. More results to come!
And, who knows how scientists 20, 50, or 100+ years will use these specimens.
Below is a sampling of some recollections from April 27, 2017 in Fox Chapel, Pennsylvania (near Pittsburgh). Note the striking differences in stages of flowering development between 1900 and 2017. The specimens on the left were collected by the first curator of botany at the museum, John Shafer.
Bloodroot (Sanguinaria canadensis): collected 117 years apart
Spring beauty (Claytonia virginica): 117 years apart
Witch hazel (Hammamelis virginiana): 133 years apart
Dutchman's breeches (Dicentra cucullaria): 117 years apart
Spicebush (Lindera benzoin): 117 years apart
We don’t always think of trees when we think spring wildflowers. But trees can have flowers too. Many trees flower in early spring, before leafing out. Many of these flowers are small and inconspicuous, and wind pollinated. This specimen of sugar maple (Acer saccharum) was collected in April 1898 in Olena, Ohio. This specimen was collected by Otto Jennings, one of the first botany curators at the Carnegie Museum. But this specimen is especially cool because it was one of his first collections, collected in his hometown, years before he became curator.
Jennings (1877-1964) was born on a farm in Olena, Ohio. He collected this species in Olena when he was 21 years old, the year he started as a student at the Ohio State University. Jennings started his 60-year tenure at the Carnegie Museum six years later, in 1904. He made many contributions throughout his career, serving as the Curator of Botany, Director of Education, and eventually Director of the Carnegie Museum of Natural History. He also was Professor of Head of the Department of Biological Sciences at the University of Pittsburgh, having advised many students. His legacy remains to this day for his influence on the museum, botany, conservation, and environmental education.
Keep an eye out for these bright yellow flowers blooming now along creeks across southwestern Pennsylvania. This specimen of lesser celandine (Ficaria verna, formerly known as Ranunculus ficaria) was collected in Edgeworth, Pennsylvania along Little Sewickley Creek by Myrta Macdonald and Jane Konrad in April 18, 1986. Native to Europe, lesser celandine was likely first introduced to the United States into gardens for ornamental purposes. It is a spring ephemeral, meaning it blooms early in the spring and goes dormant by summer. Lesser celandine is among the earliest species to bloom in the spring, with bright yellow flowers. In the past several decades, this species has become more and more common in southwestern Pennsylvania. It grows in open woods, especially in moist soils along streams. It forms dense mats that carpet the ground, capable of choking out native plants.
Specimen below: Lesser celandine specimen from its native range in England, collected on April 13, 1826.
Invasive lesser celandine is easily confused with the native wetland plant, marsh marigold (Caltha palustris). Marsh marigold is found in somewhat similar habitats and has a similar appearance as lesser celandine. However, there are several major differences. Most notable, marsh marigold does not form dense, continuous mats along the ground, but instead plants are distinctly separate (although can be large and robust). Also, lesser celandine has tuberous roots, while marsh marigold does not. Compared to lesser celandine, marsh marigold is found in wetter habitats, has fewer flower petals (5-9 in marsh marigold vs. >8 in lesser celandine), and has larger leaves that are more rounded.
Specimen below: Be careful not to confuse lesser celandine (Ficaria verna) with the Pennsylvania native wetland species, marsh marigold (Caltha palustris). This marsh marigold specimen was collected on April 28, 1887 in Westmoreland county, PA by P.E. Pierron. The herbarium of St. Vincent College (Latrobe, Pennsylvania) became a part of the Carnegie Museum herbarium in 1991.
We humans have moved plant species around the world at unprecedented scales. Human-mediated species introductions are a signature of the Anthropocene. Some of these non-native plant introductions were intentional, in the case of ornamental or food plants. And some of these plant introductions were accidental, often in the case of “weeds” associated with human disturbance, cities, and/or agriculture. When introduced plants can survive and sustain a population without human intervention, we call these species “naturalized.” When naturalized species are capable of reproducing at high rates and spreading across the landscape, far from the point of introduction, we call these species “invasive.” This process from introduction to naturalization to invasion can occur quickly, but in many cases, there is a lag such that species introduction to full blown invasion can take decades to realize.
Herbarium specimens play a critical role in understanding species invasions, serving as a valuable archive of introduced plants. When were species first introduced? Were they first introduced accidentally or were they intentionally planted in gardens? Where were species first introduced? Were they introduced multiple times at multiple locations? How have these introduced species spread in the decades to centuries since introduction? Have their morphology or genetic makeup changed since introduction? Which introduced species become naturalized, which become invasive, and which species fail to establish altogether? These are just a few of the many questions that can be answered using herbarium specimens.
There aren’t many elms on most streets named “Elm Street” anymore. With its majestic arching branches, American elm (Ulmus americana) is an iconic tree species native across Eastern North America. It was once a favorite ornamental shade tree planted along main streets and university campuses. However, due to Dutch Elm Disease (caused by a fungus from Asia introduced to the US in 1928) and Elms yellows (caused by a bacterial pathogen), many populations of American elm are no longer. The mall at Penn State is defined by its beautiful elms, many of which are succumbing to these diseases. This particularly iconic tree near Penn State’s Old Main had to be removed a few years ago due to Elm yellows.
This specimen of American elm was collected by Adolph Koenig on this day in 1893 in Springdale, Pennsylvania (the birthplace of environmentalist Rachel Carson). This specimen here has flowered, but leaves have not yet emerged. Adolph Koenig (1855-1904) was a Swiss born physician, professor of medicine and botany at the Pittsburgh College of Pharmacy (now the University of Pittsburgh School of Pharmacy). Many of his historic collections are in the Carnegie Museum’s herbarium, primarily collected in the Pittsburgh area in the late 1800s.
Spring leaf out is a bit “behind” in Pittsburgh this year. Well, for Norway maple in Schenley Park compared to 1948. Plant leaf out and flowering times is variable for many species each year due to differences in spring temperatures. This Norway maple specimen was collected by Botany curator Otto Jennings. Norway maple (Acer platanoides) is commonly planted across our region, common as a street tree or park plantings. Norway maple is invasive in Pennsylvania, spreading into natural habitats. Its leaves superficially resemble the well known sugar maple but has a different leaf shape. Norway maple has even been put on the Canadian 20 dollar bill instead of the native sugar maple (http://www.cbc.ca/news/canada/ottawa/canada-s-new-20-bill-at-centre-of-maple-leaf-flap-1.1343767). A good way to tell it is Norway maple is that exudes a white latex from the leaf when picked.
Keep an eye out for Norway maple over the next week! That light yellow/green you see at the tips of trees (especially along highways) in early spring is not tree leaves, but flowers. And many of these trees in urban areas around Pittsburgh are Norway maple. Many trees flower early in the spring, before they leaf out. Many tree species are primarily wind pollinated, so flowering before most species leaf out facilitates pollen to blow around with fewer obstructions.
In a long-term project initiated last year, we are recollecting specimens on the same calendar date and in the same location as historic specimens in the herbarium. These recollections will grow the herbarium with future use in mind – permitting comparisons across time, such as changes in leaf out dates, flowering, and genetic works. Long term studies (and herbarium specimens) are important to understand the effects of climate change and other human activities because of yearly variation. Check back for more on this project!
Image below: Norway maple buds today on a tree in Schenley Park, Pittsburgh (Apr 4, 2018). It is not quite ready to go. Note the buds are swollen but are not yet burst. Compare this to the specimen collected in 1948, in full flower and early stages of leaf expansion.