Flora of the Frontier: Mounting Specimens from the Wheeler Survey

1 Mounting specimens scaled
Alex Lorenz, Collections Technician
May 21, 2023
1 Mounting specimens scaled

There’s a unique thrill in preserving historical specimens. It makes history real and gives me an affinity for the individuals who were really there at the time the specimens were collected. Sometimes, when we’re lucky, botanical specimens come with exciting little clues that reveal the sweeping history of 19th century America.

There are many ways to preserve biological specimens, depending on their type and intended use. For example, animals might be prepared as taxidermy mounts or submerged in jars of various liquid chemicals. When it comes to botanical specimens, the plants are simply pressed and dried, much the same way you would press a flower in an old book. A botanist collecting in the field will use a specialized plant press to clamp layers of specimens together between sheets of paper and cardboard. After the plants are collected and dried, they find their way to an herbarium collection where staff and volunteers complete the preparation by gluing the specimens and their labels to archival herbarium sheets (this is my favorite part of the job). Mounting plants this way is important for a few reasons. It makes the specimens easy to organize and helps keep them safe from physical damage, but it also highlights important features that scientists are likely to study in the future. When pressing and mounting plants, it is preferable to position them where flowers, fruits, roots, and the tops and bottoms of leaves are all visible at the same time. This gives botanists the maximum amount of information to work with. Even after mounting is complete, the preservation process is never quite finished. We continuously protect our collections by storing them in a controlled environment (temperature, light, relative humidity, etc.) while regularly monitoring the space for hungry insect pests.

We are currently working toward fully digitizing the herbarium backlog, which includes many specimens that have remained unmounted since they were collected in the 1800s.

Unwrapping these plants from the original papers they were pressed in is like opening a time capsule, especially when those papers happen to be newspapers. It’s easy to get lost in the headlines.

On many occasions, I’ve been completely distracted, blissfully reading dispatches from the Spanish-American War, Presidential debates, revolutions in milk pasteurization, and everything in between. Occasionally something in the package catches my eye that confuses me and requires a little bit of research. Recently it was a label that caught my attention. Collectors make individual labels that store all the important information about their specimens, such as the date they were collected, place of collection, scientific name, unique collector number, and sometimes the name of the institution or expedition for which they were collected.

2 Specimen label 2048x860

Label from an herbarium specimen. Printed text reads: “Explorations and Surveys West of the 100th Meridian. Corps of Engineers, U.S. Army. Lieutenant G. M. Wheeler, Commanding. Expedition of 1873.”

When confronted with the information on this label, I wondered, why would the Army be collecting plants in Colorado? The answer requires a lot of historical context and I was all too happy to use my librarian skills to figure it out. Here it goes.

The period between the Civil War and the end of the 19th century was a time of fast economic and territorial expansion in the United States. The “Gilded Age” saw populations and industries grow rapidly, along with developments in science and engineering, culminating in a desire to explore and exploit more fully the lands west of the Mississippi River. Multiple government sponsored explorations of the western territories were happening simultaneously around the 1870s, all with their own overlapping objectives. Chief among these objectives was the identification of natural resources that could be used by future settlers, such as timber, water, farmable land, and mineable minerals. It must be noted that this type of exploration typically foreshadowed the removal of Indigenous people from their ancestral homes across North America. Preparing for land disputes with the Native Americans, the government began to install a military presence in the West ahead of the arrival of settlers.

“The Wheeler Survey,” otherwise known as the “U.S. Geographical Explorations and Surveys West of the 100th Meridian,” was a nine year expedition named for its leader, Lieutenant George M. Wheeler, whose goal was to produce detailed maps of the entire western half of the United States and identify locations for military infrastructure such as outposts and communication lines. Although the expedition primarily served strategic purposes, the party included a number of scientists including astronomers, meteorologists, and naturalists who would make large collections in zoology, paleontology, and botany along the way. These collections served both academic and economic purposes. They would be preserved for study in museum collections, but the botanical specimens in particular were important for documenting the agricultural potential of the territories, which was essential for the planning of future settlements.

3 Survey View umbrella

Wheeler Survey view of the American West (Timothy O’Sullivan, 1871-1874), from Library of Congress.

4 Survey View mountain

Wheeler Survey view of the American West (Timothy O’Sullivan, 1871-1874), from Library of Congress.

Using historical documentation from online archives and our own museum library, I can more or less retrace the steps of the very specimens I am mounting today. Annual reports and progress maps published by the government record the itineraries, collections, and personnel of the expedition. We know from our specimen labels, like the one shown above, that the plants were collected by a botanist named John Wolfe, whose name also appears in the official reports from the field season of 1873. The expedition was broken up into multiple smaller parties that would explore different territories simultaneously. Our collector Professor Wolfe was a member of the Colorado party under Lieutenant W. L. Marshall, whose activities are documented in the progress map below. The blue grid marks on the map show the overall goal of the expedition, covering the entire western half of the country, while the areas shaded in gray show the parts that had been surveyed by 1873. We know from the progress map and other documents that the party started the season in Denver and explored a large portion of south-central Colorado.

5 Progress Map whole

Expedition progress map of 1873. (David Rumsey Map Collection, David Rumsey Map Center, Stanford Libraries, CC BY-NC-SA 3.0)

6 Progress Map inset

Expedition progress map of 1873 with inset showing the Colorado survey area. (David Rumsey Map Collection, David Rumsey Map Center, Stanford Libraries, CC BY-NC-SA 3.0)

7 Georeference map

Map showing collecting localities of botany specimens in the collection from the Wheeler Survey. Using a process called georeferencing, we can visualize our cataloged specimens as points on a digital map. As you can see, the locality data confirms that our specimens were collected within the area shaded on the historic map.

So, how did these specimens end up with us in Chicago? Being a federal expedition, all collections from the field each year were deposited first in the National Museum of the Smithsonian Institution in Washington, DC. Luckily, many duplicate specimens were collected so they could be distributed to other institutions for study, including the Chicago Academy of Sciences. Interestingly, according to the reports, a fraction of the 1871 collections were destroyed in the Great Chicago Fire. It’s unclear if the collections were in the Academy’s possession at the time, or if they were en route to DC and just passed through Chicago with bad timing.

Of the specimens that survived their transcontinental odyssey, a few haven’t exactly stood the test of time. At some point in the last century and a half, pests found their way into John Wolfe’s unmounted specimens and had a feast. While most of the specimens are still in very fine condition, some of them unfortunately have severe insect damage. Tiny reddish-brown insects called drugstore beetles still lay between the pressing papers alongside the plants they vandalized, probably dead for a very long time. Whenever we find pest-damaged specimens, we process them in a freezer to kill off any insects or larvae that might still be alive. As I continue mounting, I use tweezers to collect the bodies of these tiny beetles and drop them into a glass vial. Gross, I know, but saving them for future reference will actually help us in our ongoing pest management efforts.

8 Specimen with beetle scaled

Drugstore beetles Stegobium paniceum, a common museum pest.

9 Beetles in vial scaled
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Drugstore beetles Stegobium paniceum, a common museum pest.

I enjoy mounting botanical specimens because it’s a necessarily slow and methodical task that also lets me use my arts and crafts skills. It’s pleasantly meditative and gives me a lot of time to contemplate exactly what I’m doing and what it means to me. Contact with historical objects gives me a real sense of continuity between the past and present. It pulls history off the page and reminds me that these events really happened and made a lasting difference, for better or worse. It’s not lost on me that the histories of collecting and colonization often go hand-in-hand, and the Wheeler Survey was certainly no exception. While its collections directly contributed to our knowledge of biodiversity and increased public interest in natural history, members of the very same expedition were guilty of unethical and unscientific practices, such as removing human remains from Native American burial sites, which also ended up in various museum collections. Reckoning with this complicated legacy is a defining feature of the museum profession in the 21st century. As for me, I find myself empathizing with the collectors represented in our herbarium. By handling the specimens and data from individual collectors, we get to know them a little bit. We begin to recognize the specific quirks of their handwriting and we start to understand where they’ve been and who they knew. I’ve picked up a new passion for American history, simply because every handwritten label makes me wonder what life looked like back then, what people were thinking about, what was in the newspaper that day, etc. The Wheeler Survey fascinated me instantly because it’s one of the few cases in my experience when all the answers to my questions were readily available in recorded history.

11 Specimen mounted one scaled

Herbarium specimens collected during the Wheeler Survey, recently mounted and digitized.

12 Specimen Mounted two scaled

So, what was the impact of this whole endeavor? This expedition and its contemporaries, together known as the “Four Great Surveys of the West,” were part of a movement that permanently changed the natural and cultural landscape of the continent. They also represented the end of an era of military controlled scientific explorations. Rivalry and redundancy among the different federal expeditions eventually led to their termination and consolidation into the organization we know as the U.S. Geological Survey in 1879, which remains a major source of scientific data on ecosystems, climate change, and resource management. We happen to have in our herbarium a fraction of a superlatively large collection, according to Lt. Marshall of the Wheeler Survey:

“Dr. J.T. Rothrock and assistant John Wolfe were offered every facility and aid in my power in making collections in natural history, and the results, especially in botany, have probably never been equaled by any exploring or surveying expedition to the West. Nearly 12,000 specimens of plants from over 1,100 different species and large collections in other branches of natural history were gathered by these gentlemen and are now being worked up.”

-Lt. W. L. Marshall

It’s a privilege to play a small part in the story of these specimens, as we continue “working them up” a hundred and fifty years later.


Government Printing Office, & Rothrock, J. T., Catalogue of plants collected in the years 1871, 1872 and 1873 : with descriptions of new species / (1874). Washington D.C.; Engineer Department US Army. Retrieved 2023, from https://catalog.hathitrust.org/Record/100624540.

Government Printing Office, & Wheeler, G. M., Annual report upon the United States geographical surveys west of the one hundredth meridian in the states and territories of California, Oregon, Nevada, Texas, Arizona, Colorado, Idaho, Montana, New Mexico, Utah, and Wyoming 1–114 (1874). Washington D.C.; Engineer Department US Army. Retrieved from https://catalog.hathitrust.org/Record/006174102.

Rabbitt, M. C. (2019). The United States Geological Survey: 1879-1989. U.S. Geological Survey Circular 1050. Retrieved March 2, 2023, from https://pubs.usgs.gov/circ/c1050/

Schubert, F. N. (1980). Vanguard of expansion: Army Engineers in the Trans-mississippi west, 1819-1879. U.S. Army Corps of Engineers Digital Library. Historical Division, Office of Administrative Services, Office of the Chief of Engineers. Retrieved 2023, from https://usace.contentdm.oclc.org/digital/collection/p16021coll4/id/265/rec/30.

O’Sullivan, T. H., Wheeler Survey views of the American West, 1871-1874 (1874). Washington D.C.; War Dept., Corps of Engineers, U.S.A.. Retrieved 2023, from https://www.loc.gov/pictures/item/2005690349/.

Progress Map Of Lines And Areas Of Explorations And Surveys. David Rumsey Historical Map Collection. (n.d.). Retrieved March 2, 2023, from https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~298~30005:Progress-Map-Of-Lines-And-Areas-Of-?title=Search%2BResults%3A%2BList_No%2Bequal%2Bto%2B%272738.003%27&thumbnailViewUrlKey=link.view.search.url&fullTextSearchChecked=&annotSearchChecked=&dateRangeSearchChecked=&showShareIIIFLink=true&helpUrl=https%3A%2F%2Fdocumentation.lunaimaging.com%2Fdisplay%2FV75D%2FLUNA%2BViewer%23LUNAViewer-LUNAViewer&showTip=false&showTipAdvancedSearch=false&advancedSearchUrl=https%3A%2F%2Fdocumentation.lunaimaging.com%2Fdisplay%2FV75D%2FSearching%23Searching-Searching

Viola, H. J. (1987). Exploring the West. Smithsonian Books.

Wheeler Survey: Overview. Headquarters U.S. Army Corps of Engineers. (2021, March). Retrieved March 2, 2023, from https://www.usace.army.mil/About/History/Historical-Vignettes/Parks-and-Monuments/142-Wheeler-Overview/

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