Erin Southerland

May 22, 2024 by Erin Southerland

Botanists Gone Wild! Perspectives from the Record-Breaking Finish for City Nature Challenge 2024

by Jessica Romano

Every spring people all over the world join in the City Nature Challenge, a global effort to safely document and identify nature through the free and easy-to-use iNaturalist app. For the seventh consecutive year, Carnegie Museum of Natural History staff were among the participants taking on the challenge in and around the Pittsburgh region – and in 2024, the results were record-breaking! Totals for regional participants, identifiers, observations, and number of species hit their highest in the history of the challenge, thanks to a combination of warm, dry spring weather and dedication from participants. Observations and identifications made during the challenge are shared with scientists around the world, helping to both document and better understand the diversity of species around us.

Here are the totals from the Pittsburgh Region City Nature Challenge 2024 (CNC) – which are all records for this region’s participation!

Total participants who made observations: 643

Total participants who made identifications: 562

Total observations made: 10,050

Total species identified: 1,753

Total identifications: 16,875

Plants topped the list for observed species, with about 46% of the total, followed by insects with about 27% of the total. Other species identified but in smaller totals include fungi, birds, arachnids, mammals, reptiles, amphibians, and mollusks.

Mayapple (Podophyllum peltatum) took the top spot overall. This native plant species sprouts early in spring with long stems and umbrella-like leaves. The rest of the top 10 species are all plants, with the exception of the Red Admiral (Vanessa Atalanta), a beautiful butterfly with red bands on the wings. The most observed bird, the American Robin (Turdus migratorius),took spot 17, and at spot 26, the White-tailed Deer (Odocoileus virginianus) was the most observed mammal.

*The lovely Common Blue Violet (*Viola sororia) came in third place on the list of observed species.

With plants claiming nine of the top ten spots, it’s fitting to get perspective from the museum’s Section of Botany, who not only participate, but whose dedication puts them at the top of the list. Although they are literally professionals at looking for plants, the common message from the Botany staff is that anyone can do this challenge! The objective is to document nature all around us, from parks to neighborhood streets to city blocks and beyond.

Reflections from the Section of Botany Scientists

Curatorial Assistant Alyssa Landa made a point to visit similar spots that she visited last year, as well as around her yard and street to look at things she walks past every day. “CNC is a great reminder to check out places near me,” Alyssa said. “The big thing for me this year is just the number of new-to-me species I was able to log, just by taking that little bit of extra time to pay attention to what’s around that I might not otherwise be drawn to or notice! This time of year is always really exciting to me, and CNC is a fun reminder that there’s still so much to learn. It’s also a reminder to revisit my old, well-known (plant) friends too.” And her efforts made a difference! Alyssa logged the second highest total identifications, putting her expertise to excellent use.

A steadfast champion for the City Nature Challenge, Associate Curator of Botany Mason Heberling uses the challenge to check out the woods nearby where he lives. “I get caught up in other things and forget to appreciate the hyper-local diversity, within walking distance,” Mason said. “I make it a point to visit the same woods by my house every CNC.” Despite travelling out of the area for much of the challenge, Mason logged nearly 100 local observations!

And then there’s Bonnie Isaac, the section’s Collection Manager. Although City Nature Challenge is not a competition, it’s worth noting and applauding Bonnie’s efforts – she logged the highest number of both observations and identifications in the Pittsburgh region this year! She made 607 observations, which totaled 343 different species, and identified a whopping 1,697 entries! Bonnie shared her reflections about the challenge and described why it’s so important to her.

“When I was young, I could not spend enough time outdoors. I was outside from sunup till sundown or until my folks came looking for me. My curiosity led me to want to know what everything I encountered was. One year one of my sisters gave me a Peterson field guide for Christmas. This led me to discover that there was a whole series of Peterson field guides. Thus began my collecting career. I had to have every Peterson Field Guide that came out. (I now have a complete set of Peterson Field Guides, leather bound editions.) With these guides I could go out and try to identify everything I saw. I was in heaven. I am also a very competitive person. The City Nature Challenge takes what I love to do and makes it into a bit of a competition. I don’t live in the Pittsburgh City Nature Challenge region. I live in Lawrence County. During the pandemic the best I could do was help with identifying observations. Now that I can travel to the Pittsburgh region during the City Nature Challenge. Game on!” – Bonnie Isaac

Of Bonnie’s impressive collection of field guides, the first one she received was not plants, but animal tracks! It was written by Olaus J. Murie, a former employee of Carnegie Museum of Natural History who became a world famous biologist. Image credit: Bonnie Isaac.

For this year’s challenge, Bonnie visited Raccoon Creek State Park, Moraine State Park, Bradys Run Park, and Brush Creek Park. “The City Nature Challenge gives me a chance to get outside and see how many different things I can find,” Bonnie said. “Every year I challenge myself to find more species than I did the previous year. I also find identifying observations made by others somewhat satisfying. I get a chance to hone my identification skills and I get to see what others have found.”

Even for a botanist with decades of experience like Bonnie, each year brings surprises. “Every year there are surprises that I didn’t expect. I’ll discover that something is blooming that I didn’t think would be blooming yet, or I might find that someone found a plant growing in an area where I wouldn’t have expected it.”

*Bonnie has never seen an all-white Blue-eyed Mary (*Collinsia verna). She was excited to see that iNaturalist user “bquail” found some during the challenge. Image credit: © bquail via iNaturalist, CC BY-NC

Bonnie continued, “The top observations tend to be some of the same things, many plants that are not native to the area. It’s the things with only a couple observations that I find the most interesting. It’s these unusual observations that keep me eager to see what nifty things are being found basically in our own backyards. It also keeps me energized to get out and find more and to look closer for the minute details that might separate one species from another.”

The iNaturalist app also allows for recordings of bird song, frog calls, and other sounds. Bonnie connected with a user who identified a unique feature on one of her uploaded recordings. “One of the surprises for me was someone contacting me to let me know that one of my bird recordings had gray tree frogs singing in the background.”

*Bonnie’s favorite observation of 2024 was this Goldenseal, just coming into bloom. Image credit: Bonnie Isaac.*

A Global Effort with Big Results

City Nature Challenge 2024 was not just a success in Pittsburgh – globally the number of cities participating increased to 690 this year, a big jump from 482 cities in 2023! Here are a few of the worldwide stats:

Total participants: 83,528 in 690 cities in 51 countries

Total observations made: 2.4 million

Total species identified: 65,682

The big winner across the board, with most observations, species, and participants is La Paz, Bolivia!

The City Nature Challenge returns next spring. Let’s see if we can build on the truly remarkable success of 2024!

Jessica Romano is Museum Education Writer at Carnegie Museum of Natural History.

Slipper Snails Slide Between Sexes in Stacks

Or, Crepidula fornicata say, “Trans Rights!”

…if they don’t get eaten by their siblings first.

by Sabrina Spiher Robinson

*A pair of slipper snails seen from below. Image credit: Ecomare/Sytske Dijksen, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons*

A stack of Crepidula fornicata, grown together (with a little chiton, another type of mollusk, hanging out on the top of the family). — *A stack of* Crepidula fornicata, grown together (with a little chiton, another type of mollusk, hanging out on the top of the family). *Image credit: User Lamiot on fr.wikipedia, CC BY-SA 1.0 https://creativecommons.org/licenses/by-sa/1.0, via Wikimedia Commons*

Slipper snails, Crepidula fornicata, are a common find for shell collectors along the American east coast, and in some places on the west coast as well, where they have been accidentally introduced as an invasive species. But just because they’re common, doesn’t mean they’re not interesting – in fact, they’re one of the most well-studied marine snails, and all of that study has revealed a creature with a fascinating life cycle.

Crepidula are protandrous hermaphrodites – this means that all slipper snails begin their lives as male, and end their lives as female. As juveniles, they wander over the substrate, preferring hard surfaces like rocks, dock pilings, other shells, and even horseshoe crabs. But most C. fornicata will choose to settle on top of another C. fornicata, who might be settled atop another, and another, and so on. They live in stacks, sometimes of up to a dozen animals, one balancing on top of the next until their shells grow around each other, and they can no longer move, becoming sessile (stationary) by default.

Of course, a stack of all males won’t get very far reproductively. So, it’s time for at least a few C. fornicata to begin the next stage in their lives, and transition to females. Several things influence when the change takes place, primarily the animal’s size, because producing gametes is energetically costly: more sperm takes more energy than less sperm, and eggs take more energy than sperm altogether. But it’s not so straightforward as just growing to a certain size and changing sex. If there are no females around, for instance, some males will transition to females at smaller sizes than they usually would.¹ Alan Carillo-Boltodano and Rachel Collin write:

“In our experiment, pairs of snails (one small and one large) were kept in cups, either together or partitioned off with fine or coarse mesh, or partitioned, but switched from side to side to allow contact with the cup mate’s pedal mucus. The larger snails that were allowed contact with the smaller companions grew faster, and generally changed sex sooner, than did the larger snails in the barrier treatments, which allowed no physical contact. The smaller snails that were allowed contact with the larger cup mate delayed sex change compared to those separated from their cup mates … Our results suggest that the cue that affects size and time to sex change requires some kind of physical interaction that is lost when the snails are separated. Furthermore, contact with another snail’s pedal mucus does not compensate for the loss of physical contact.”²

In other words, when the slipper snails are in actual contact with each other, they seem to send signals to one another that help to coordinate growth and sex change.

In general, though, males will wait until they’re a certain size to transition, because larger males are more reproductively successful than smaller males, as determined by experiments that genetically test offspring to see whose genes were most successful in the stack. There’s one exception to this though – sneaky little guys! Male Crepidula inseminate females directly, so in general the male right on top of the female at the bottom of the stack will be the most successful fertilizer, and then the male on top of him, and then the others on top of them can’t reach and are out of luck for the moment. But! The smallest juvenile Crepidula, who have not yet chosen a stack of their own, have been found to sneak up on the substrate next to the female, inseminate her, and sneak away, using a strategy that gets around “bigger = more sperm.”³

Larger males might have more reproductive success than smaller males, but no one has more reproductive success than slipper snails who have transitioned to females. Eggs are a much bigger energy investment for an animal than sperm are, and so becoming a female requires a certain size to make the transition worthwhile. But once a slipper snail is female, she has a couple reproductive advantages: in the first place, she can hoard sperm for a long time, including her own from when she was a male, so she always has plenty of material to fertilize her eggs. This also means that while only a third or a quarter of the embryos will have a given male’s DNA, they’ll all have hers. Secondly, Crepidula females brood their young. Unlike many marine mollusks, who release their eggs and sperm into the water column where they meet and the embryo has to grow up among the plankton, at risk of becoming a meal for many things before they ever even get to grow into larvae, Crepidula keep their eggs in brooding pouches. Females keep between 15 and 20 pouches inside their shells, each containing between 50 and 450 embryos. She’ll brood them until they turn into larvae that can swim about on their own, keeping them safe to grow at least for a little while.

And thus, every Crepidula fornicata begins their life as a tiny, and sometimes sneaky, roaming male, sowing his wild oats; eventually he finds a nice stack to settle down on to become a dad; and then they transition sexes and live out her days as mother and base of the stack, brooding little babies in safety until they’re ready to hatch into larvae. Slipper snails make small stacks, but big happy families.

However, perhaps nowhere is safe. Once the eggs are brooding in their capsules, the mother slipper snail has no way to transfer additional nutrients or oxygen to the embryos. This environment of scarcity leads some species of Crepidula embryos to start cannibalizing each other! The embryos of Crepidula coquimbensis, a species of Crepidula first described in Chile, have at least been found to be choosy about eating their brothers and sisters. Brood capsules are fertilized by multiple males, meaning all the embryos have the same mother, but not every embryo has the same father. It was discovered that cannibalistic embryos were much more likely to eat their half-siblings than their full siblings, thus protecting embryos they shared a complete set of DNA with. It’s still not known how these embryos recognize kinship, though.⁴ In another species of Crepidula, Crepidula navicella, a gene in some of the embryos in each capsule switches on and arrests their development, basically turning them into meals for their siblings, a genetic predisposition to being either a cannibalizer or a cannibalizee.⁵

Of course, once the larvae are released into open water, all bets are off, and a lot of filter-feeding animals, including other mollusks, including other Crepidula, might eat them. However, Jan Pechenik reports:

“… in our study the same adults usually ingested their own larvae at much slower rates than predicted from the rates at which they cleared water of phytoplankton. These slower rates may in part reflect an inability or reluctance of adults to ingest particles of such large size … However, most of the larvae that we observed being entrained into adult feeding currents were ingested, and later appeared in feces, and adults were capable of ingesting larvae that were larger … Thus, lower than predicted rates of [larvae eating] by C. fornicata more likely reflect larval behavior – deliberate or not – reducing the likelihood of [getting drawn] into the adult feeding current, as suggested previously from studies with [other marine filter feeders].”⁶

At least baby Crepidula, once free, seem to have developed a way to avoid being eaten by their parents, if not their siblings!

Sabrina Spiher Robinson is Collection Assistant for the Section of Mollusks at Carnegie Museum of Natural History.

References:

[1] Proestou, Dina A., Goldsmith, Marian, Twombly, Sarah (2008) “Patterns of Male Reproductive Success in Crepidula fornicata Provide New Insight for Sex Allocation and Optimal Sex Change.” The Biological Bulletin (Lancaster), vol. 214, no. 2, 2008, pp. 194–202, https://doi.org/10.2307/25066676.

[2] Carrillo-Baltodano, Allan, and Collin, Rachel (2015). “Crepidula Slipper Limpets Alter Sex Change in Response to Physical Contact with Conspecifics.” The Biological Bulletin (Lancaster), vol. 229, no. 3, 2015, pp. 232–42, https://doi.org/10.1086/BBLv229n3p232.

[3] Broquet, Thomas, et al. “The Size Advantage Model of Sex Allocation in the Protandrous Sex-Changer Crepidula fornicata: Role of the Mating System, Sperm Storage, and Male Mobility.” The American Naturalist, vol. 186, no. 3, 2015, pp. 404–20, https://doi.org/10.1086/682361.

[4] Brante A, Fernández M, Viard F (2013) Non-Random Sibling Cannibalism in the Marine Gastropod Crepidula coquimbensis. PLoS ONE 8(6): e67050, doi:10.1371/journal.pone.0067050

[5] Lesoway, MP, Collin, R, Abouheif, E. (2017) “Early activation of MAPK and apoptosis in nutritive embryos of calyptraeid gastropods.” J. Exp. Zool. (Mol. Dev. Evol.) 328B: 449–461. doi:10.1002/jez.b.22745.

[6] Pechenik, Jan, Blanchard, Michel, Rotjan, Randi (2004) “Susceptibility of Larval Crepidula fornicata to Predation by Suspension-Feeding Adults.” Journal of Experimental Marine Biology and Ecology., vol. 306, no. 1, 2004, pp. 75–94, https://doi.org/10.1016/j.jembe.2004.01.004.

Pressed Flowers Come Alive by Telling Their Pollination Story

by Nathália Susin Streher

Do you ever wonder what made you pursue your dreams in life? When I ask myself this question, it inevitably takes me back to my childhood and the indelible memories that growing up in the most biodiverse country in the world left on me. From the diversity of fruit trees and the tiny animals that crawled them in my backyard to the varied ecosystems in the surrounding areas, living in Brazil has shaped my perception of nature and sparked a singular curiosity about the variety of forms and interactions I could observe. As the little scientist in me grew up, fueled by the fascination with the beautiful mysteries of flowers, it naturally guided me toward the path of studying plants and their interactions.

As I stepped into the world of science, my first paid opportunity as an undergrad in biology was in a small herbarium. There I learned about preserving plant specimens collected from nature and their importance for identification and classification of plant species. What I did not realize back then was that herbaria store more than just names and relations among species; they also provide a means to investigate ecological interactions like the ones that captivated me as a child. I kept that flame of curiosity from my childhood alive and came to the US as a postdoc researcher. My research group at the University of Pittsburgh and I have been incorporating some unconventional uses of herbarium material into our research. In a recent scientific publication, we used herbarium specimens (many sourced from the CMNH herbarium) to explore a crucial ecological mutualism between animals that visit flowers for food and plants that require go-betweens to transport their pollen—a process called pollination.

In pollination biology, it is common to investigate floral characteristics because they play a crucial role in mediating plant interactions with their pollinators. For example, plants with long floral tubes are typically pollinated by morphologically matching long-tongued pollinators. While certain floral traits, such as visible color and scent, may be altered or completely lost during the drying process of plant specimens, many of the other characteristics remain accessible even after years of preservation. Thus, as long as the herbarium sheet contains at least one flower, valuable biological information can be extracted to understand plant-pollinator interactions.

In this study, we used herbarium specimens to reveal the network of past plant-pollinator relationships. Specifically, we sampled a small piece of the flower, the stigma, which is the structure that receives pollen grains delivered by pollinators. As pollinators may visit several plant species flowering together, inspecting stigmas can unveil a plant’s pollination story. By assessing the diversity of pollen grains morphologically distinct from the target species, we gain insights into whether the target species interacted with many or only a few other plant species through pollinator sharing.

images of a pressed flower with close-ups of the stigma, anther, and pollen grains

Leveraging herbarium specimens for ecological questions offers a unique advantage, as they provide historical, spatial, and long-term perspectives to scientific studies—dimensions that may otherwise be challenging to attain. In studies of plant-pollinator interactions, researchers often rely on direct pollinator observation data, which, while ideal, has limitations such as being time-consuming, costly, and dependent on various conditions. Pollen deposited on stigmas of herbarium specimens arises as a valuable alternative when direct pollinator observation is unfeasible. Herbaria offer scientists a convenient way to compare numerous plant species from around the world. Actively incorporating these specimens into research not only keeps the collections dynamic but also magnifies their overall significance. Much like the plant-pollinator interaction—it’s a win-win scenario. I hope our work inspires others to perceive herbarium collections as guardians of biodiversity and encourages scientists to unlock the hidden potential of their precious specimens.

Beyond the scientific excitement of unraveling the pollination story within herbarium specimens, I once again seemed to have missed yet another potential interaction they could reveal. While going through the cabinets housing the specimens at CMNH, I unexpectedly encountered plants collected from the same region where I was born and raised in Brazil. I never thought that an old, dried plant could make me feel closer to my homeland. Living abroad to pursue the scientific dream is no easy feat—different language, different culture. But that moment was a reminder of my childhood connection with nature that brought me here. Now, I see herbaria not only as guardians of biodiversity but also as promoters of a sense of belonging in us.

Collage of images, clockwise from top left: the author inspecting flower traits and age seven; the author and her friend during their early yeas as undergrads, learning how to press plant specimens in Brazil; an herbarium specimen with the following note from the author "On of the plant specimens that I found in the CMNH herbarium fostered a sense of connection between me and my homeland. The specimen was collected just around 80 miles from where I was born and originally deposited in the herbarium of my hometown"; the author sampling stigmas in the herbarium

Nathália Susin Streher is a postdoctoral research associate in the Ashman Lab of University of Pittsburgh.

Type Specimens: What are they and why are they important?

by Timothy A. Pearce and Rachel Thomas Beckel

What do we mean when we say we have type specimens in the Carnegie Museum of Natural History (CMNH) collections?

Type specimens are (usually) the specimen(s) a person describing a new species looks at as they write the description (it’s this tall, this wide, this color, sculptured with bumps like this, etc.) and type specimens are the official name bearers for the whole species.

There are many kinds of type specimens, but the most important kind is the holotype. Paratypes (other specimens the original describer believes are the same new taxon) are also important, but holotypes are the most important. Two other kinds of type specimen are lectotypes (selected from the paratypes if the holotype is lost) and neotypes (selected from any specimen if all type material is lost). Every time we add another holotype it bolsters the significance of CMNH’s already significant collections. It raises our visibility on the “radar” of researchers and puts us on the map for that taxon.

Carnegie Museum collaborator Dr. Aydin Örstan recently named a new subspecies of snail Albinaria coa tek (Örstan & Yildirim 2023). He deposited the holotype and 12 paratypes of the new subspecies in the Mollusks collection at CMNH.

*Holotype of* Albinaria coa tek *Örstan, 2023. Image from Örstan & Yildirim (2023).*

If a researcher wants to know if they have found another specimen of Dr. Örstan’s new subspecies, they could read his description. However, to be absolutely sure, a researcher might need to compare their finding to the type specimen.

Think of types as the gold standard. Because of their importance to nomenclature and taxonomy (the science of naming species), most museums (including CMNH) keep their type specimens securely locked in a special cabinet.

With regard to this land snail holotype, for Carnegie Museum to have the holotype of Albinaria coa tek means that people studying that subspecies or closely related taxa might need to travel to the museum to examine the type specimen or ask for additional information about it. For their research paper to be complete, they would need to refer to that holotype specimen. In addition to the holotype, Dr. Örstan gave CMNH paratypes of Albinaria coa tek, which can be important for understanding the range of variation in the subspecies.

Albinaria are land snails that occur in SE Europe and the Middle East and are typically found on limestone. In some cases, they appear to have been able to form new colonies when ancient humans moved limestone around for buildings (the snails likely hitchhiked on the limestone blocks). That means we can trace trade routes over which ancient humans were moving limestone.

The family Clausiliidae (which contains the genus Albinaria) are of interest because they bear a clausilium, a kind of door for closing the shell (hence the common name “door snails”), which is unique to the family and is very different from the operculum, which is a different kind of door in many sea snails and some land snails. Furthermore, most snails in the family Clausiliidae coil counterclockwise, which is the opposite direction of more than 99% of all other snails. Additionally, Clausiliidae have a peculiar global distribution, being found in western Europe, Eastern Asia, and northern South America. People who study biogeography (how species came to be living where they are now) scratch their heads wondering how Clausiliidae came to be living in those three separate places without any individuals being found in between – for example, if they migrated from Europe to northern South America, why don’t any Clausiliidae occur in North America?

In addition to this new holotype (and paratypes) in the Section of Mollusks, holotype specimens of new species of vertebrates and paratypes of a new species of insect were named in 2023 and deposited in the relevant sections of the CMNH collection:

Pietro Calzoni, from the Universitá di Padova, Italy, and colleagues designated a CMNH Vertebrate Paleontology fossil as the holotype of a new bony fish species, Rhamphosus tubulirostris (Calzoni et al. 2023).

Three new species of the insectivore mammal genus Plagioctenoides (P. cryptos, P. dawsonae, and P.goliath), and one new species of Cuetholestes (C. acerbus), were recently named from CMNH Vertebrate Paleontology fossils (Jones and Beard 2023).

A CMNH Vertebrate Paleontology gekko fossil was designated as the holotype of Limnoscansor digitatellus (Meyer et al. 2023). CMNH visitors can view this specimen on display in the Solnhofen case in the Dinosaurs in Their Time exhibition.

A male and six female moths from the CMNH Invertebrate Zoology collection were named the new moth species Meganaclia johannae (Ignatev et al. 2023). The moths were collected between 1918 and 1925 in Cameroon and were housed in the Invertebrate Zoology collection awaiting discovery as new species.

While CMNH welcomes hundreds of thousands of visitors per year to the public galleries, scores of researchers work behind the scenes to expand our understanding of the different kinds of organisms, as evidenced by their type specimens, that are present in our incredible world. As the moth example demonstrates, Carnegie Museum of Natural History (and other museums around the world) hold specimens that have yet to be recognized as new species!

Timothy A. Pearce is Curator of Mollusks and Rachel Thomas Beckel is Administrative Coordinator for Science & Research at Carnegie Museum of Natural History.

References

Calzoni, P., J. Amalfitano, L. Giusberti, M. Carnevale, and G. Carnevale. 2023. Eocene Rhamphosisdae (Teleostei: Syngnathiformes) from the Bolca Lagerstätte, Italy. Rivista Italiana di Paleontologia e Strigrafia, 129(3): 573-607.

Ignatev, N., G.M. László, A. Paśnik, Z.F. Fric, H. Sulak, and G.C. Müller. 2023. Five new species of the genus Meganaclia Aurivillius, 1892 (Lepidoptera: Erebidae: Arctiinae: Syntomini). Zootaxa, 5296: 457–474.

Jones, M., and K.C. Beard. 2023. Nyctitheriidae (Mammalia, ?Eulipotyphla) from the Late Paleocene of Big Multi Quarry, southern Wyoming, and a revision of the subfamily Placentidentinae. Annals of Carnegie Museum, 88(2): 115-159.

Meyer, D., C.D. Brownstein, K.M. Jenkins, and J. Gauthier. 2023. A Morrison stem gekkotan reveals gecko evolution and Jurassic biogeography. Proceedings of the Royal Society B., 290: 20232284.

Örstan, A., and M.Z. Yildirim. 2023. A new insular land snail, Albinaria coa tek Örstan, from Marmaris, Türkiye (Clausiliidae: Alopiinae). Archiv für Molluskenkunde, 152(2): 175-182.

City Nature Challenge: Noticing Invasive Plants

by Rachel Reeb and Jessica Romano

This spring, thousands of people will join the City Nature Challenge, a global effort to document biodiversity safely and easily on the free iNaturalist app. Participating in the challenge is fun and rewarding – simply make observations of nature, take photos, and upload them to the app. The data collected during the challenge is shared with scientists around the world and helps them both document and better understand the diversity of species around us. This year’s challenge takes place April 25 through 28 for the observations, with a follow-up identification period from April 29 through May 1 when scientists and naturalists help observers properly identify the species they found. Participants will observe plants, insects, mammals, birds, mollusks, reptiles, amphibians, and more, right in their own neighborhoods.

Alliaria petiolate, common name Garlic Mustard, is very commonly spotted during the City Nature Challenge and is easy to identify by its broad leaves and small white flowers. Credit: Katja Schulz from Washington, D. C., USA, CC BY 2.0, via Wikimedia Commons.

To help get us ready for this year’s challenge, Rachel Reeb, postdoctoral fellow in the Section of Botany at Carnegie Museum of Natural History, created this guide to finding and understanding invasive species of plants, including species like garlic mustard that is repeatedly one of the most often observed plants during the challenge. To get started, Rachel provided helpful definitions:

Native or Indigenous species: Species that exist within an area due to natural evolution.

Introduced species: Species that have been introduced, by humans, to an area outside of its indigenous range. Roughly 25% of plant species in our environment are introduced.

Invasive species: A subset of introduced species which cause significant harm to the environment or human well-being.

Naturalized species: A subset of introduced species which do not have demonstrated impacts on the environment or human well-being.

*Lonicera maackii, known as the Amur Honeysuckle, originated in temperate areas of eastern Asia. Credit: Jay Sturner from USA, CC BY 2.0, via Wikimedia Commons.*

Observing Invasive Plants

When is the best time to spot invasive plants? In the early stages of spring! Since introduced invasive plants evolved in a different part of the world, they often have unique life cycles that start and end at a different time than the rest of the plant community. Invasive species like garlic mustard, lesser celandine, periwinkle, multiflora rose, and Amur honeysuckle are some of the first to start their life cycles in the spring, providing a surprising pop of greenery to an otherwise dormant forest understory. This ‘head start’ in the growing season gives invasive plants an advantage because they gain priority access to soil nutrients and sunlight, while other plants are still dormant.

*Ficaria verna, or Lesser Celandine, blankets the ground in Frick Park. Credit: Rachel Reeb.*

Unfortunately, what serves as an advantage for invasive plants is often a disadvantage to their neighbors, which now have a delayed start in the race to capture limited seasonal resources. Environmental experts in Pittsburgh are especially worried about the survival of rare native wildflowers, such as large white trillium, mayapple, and yellow trout lily. These plants, which have very specific habitat conditions and cannot easily relocate to new areas, are highly sensitive to changes in the environment and often cannot survive in areas where invasive plants are present.

During this year’s City Nature Challenge, we encourage you to take note of everything in nature, including the weeds. What do you notice about invasive plants in your area, like the timing of their life cycle, or how they interact with their neighbors? Have you ever wondered how these organisms came to be here? Many unwanted invasive plants were first introduced as popular garden center products. While some invasive species are now banned from sale, many can still be found in stores, like English ivy and Periwinkle vines.

*Podophyllum peltatum, common name Mayapple, is a native species in Pennsylvania and sprouts early in spring, resembling little umbrellas on the landscape. Credit: Jessica Romano.*

Here are helpful lists of species you may encounter in our area:

Invasive Species

Garlic Mustard
Lesser Celandine
Knotweed
Multiflora Rose
Amur Honeysuckle
Periwinkle / Vinca
English Ivy
Japanese Barberry
Tree of heaven

Naturalized Species

Common Dandelion
White Clover

Native Spring Wildflowers

Mayapple
Large White Trillium
Dutchman’s Breeches
Virginia Bluebells
Common Blue Violet
Yellow Trout Lily

How many of these species can you spot? Get your camera/phone/device and join the City Nature Challenge, April 25 through 28!

Rachel Reeb is a postdoctoral research fellow in the Section of Botany at Carnegie Museum of Natural History. Jessica Romano is Museum Education Writer at Carnegie Museum of Natural History.

Remembering Albert Kollar, Collection Manager of Invertebrate Paleontology

Albert D. Kollar, Collection Manager of Invertebrate Paleontology

Last year, when Albert Kollar, Collection Manager of Invertebrate Paleontology at Carnegie Museum of Natural History, was planning for, and later recovering from, knee surgeries, it was common to hear people wish him well by saying, “You’ll be back on the outcrop soon.” In the wake of his untimely death last week, those wishes are worth examining for all they capture of Albert’s generous and long-standing sharing of geologic knowledge.

Outcrop, as anyone who participated in one of his geology-focused hikes already knows, refers to the part of a rock layer that can be seen at the Earth’s surface. Pittsburgh’s location amid a deeply eroded Appalachian plateau assures a richness of local outcrops. In river and stream cuts, natural features that in many places acquired sharper edges through the construction of road or railway terraces, multiple sedimentary units appear stacked like layers of a cake. Albert had a deep and working understanding of each of these massive rock units. He could patiently explain how their differing composition implied dramatic past changes in climate, sea level, plant cover, and even continent position.

*Albert with the original Invertebrate Paleontology door.*

For prolonged discussions of local geology, Albert introduced audiences to several rock units prominent or economically important enough to have earned names, the Birmingham Shale, the Morgantown Sandstone, the Ames Limestone, and the Pittsburgh Coal. In explaining that every rock unit, whether it held fossils or not, contained a story about its formation, Albert would frequently distribute hand samples from these units. When the audience was a middle school class, the students could take the samples home, souvenirs not just from the museum, but from the outcrop.

*The Invertebrate Paleontology team doing a spotlight on Bayet fossils. Fall 2023.*

Read Blog Posts by Albert D. Kollar

Meet the Mysterious Mr. Ernest Bayet

Smoking Fossils

Carnegie’s Water Fountains

Thank you to Joann Wilson and the Invertebrate Paleontology team for the photos.

Carnegie Museum of Natural History Blog Citation Information

Blog author: McShea, Patrick
Publication date: April 16, 2024

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Remembering Albert Kollar, Collection Manager of Invertebrate Paleontology

Read Blog Posts by Albert D. Kollar

Carnegie Museum of Natural History Blog Citation Information

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