Herbaria: Specimens Get Around

Cover of Capitulum, Volume 2, Number 1

Years ago, my husband would attend meetings of the Popular Culture Association because he was interested in visual aspects of the popularization of science in 19th century magazines and books.  I of course tagged along, and soon discovered that the PCA was about much more than comic books and plastic toys.  There are dozens of sections and I found ones that dealt with material culture, the study of things—including two of my loves: natural history specimens and textiles.  Material culture deals with human-made artifacts and would seem to exclude specimens, but that’s hardly the case.  A specimen is an artifact.  A herbarium sheet is more than a plant.  It’s a piece of paper with at least one label, and the plant has been processed by humans to behave well in two dimensions.  The botanical artist Rachel Pedder-Smith wrote about herbaria and material culture in her dissertation that accompanied her spectacular painting of Kew specimens, Herbarium Specimen Painting.

Over time, a specimen accretes greater significance as more humans interact with it.  Deborah Harkness (2007) writes:  “Every time a dried plant specimen changed hands it became infused with new cultural and intellectual currency as its provenance became richer, its associations greater” (p. 31).  Often though not always, the transfer is noted physically on the sheet, making it easier to explain how a particular plant from, for example Germany, ended up in New Zealand, or why plants collected on a Captain James Cook expedition found a home in Philadelphia.  In the last three posts (1,2,3) I’ve discussed attempts to puzzle out the provenance of herbaria, now I want to take this down to the “microhistory” level and look at the travels of individual sheets. 

I got this idea from a lovely article I read in Capitulum, the recently revamped newsletter of The International Compositae Alliance (TICA).  Abigail Moore (2022) writes about a single sheet at Philadelphia’s Academy of Natural Sciences of Drexel University that has two gatherings of what is now Grindelia ciliata(Nutt.) Spreng.  The first was collected in 1819 by Thomas Nuttall, a British botanist who worked for many years in the United States and collected widely in the West.  The label just gives “Arkansas” as the locale, but in the species description, Nuttall (1821) added “on the alluvial banks of the Arkansas, and Great Salt River.”  The second gathering was from Samuel Woodhouse, who was like many collectors in the West, a U.S. Army surgeon/naturalist.  He was on the Sitgreaves Expedition 1849-1851 to map in the same region Nuttall had visited 30 years earlier.  The locale is “Cherokee Nation,” and Moore explains the technicalities of that term at the time, pointing to an area close to where Nuttall had found the first specimen.  She ends by going into the rather complex nomenclatural history of this species, explaining the various names on the labels.  It’s a lovely article and a reminder of how much can be learned from a single sheet.

In a very different example of the rich history that ANS specimens can reveal, Earle Spamer (1998) writes of 26 sheets there that were collected by Johann Reingold Forster and his son Johann Georg, naturalists on Captain James Cook’s second around-the-world voyage.  Spamer describes how much they collected and how broadly the specimens were distributed, in most cases to British or at least European herbaria.  The ANS specimens were given in 1834 by Thomas Nuttall, who apparently got them from Aylmer Bourke Lambert, an avid British botanist and collector (they are marked “Lambert Herbarium”).  Some Lewis and Clark specimens at the ANS were also once part of Lambert’s herbarium but arrived by a very different route—a story for another time (Spamer & McCourt, 2002). 

On the other side of the world, the herbarium of the Museum of New Zealand Te Papa Tongarewa has a briefer history than ANS but none-the-less an interesting collection.  Eighty-four of its specimens traveled from Japan to Russian to Britain before arriving back in the Pacific.  The Russian botanist Carl Maximowich collected in Japan from 1860-1864 and returned to Saint Petersburg with 72 chests of specimens.  The Natural History Museum, London received 1500 from this hoard, and they sent 84 on to New Zealand.  At the time, New Zealand was a young colony, trying to develop its scientific infrastructure and the museum sought assistance from London.

These specimens were part of a much larger European collection of 28,000 specimens bought from NHM by the museum’s director James Hector in 1865.  He thought Australian botanists needed a reference collection to aid in identification of the many non-native plants spreading through the colony, either inadvertently or purposefully brought in by settlers.  As often happens in understaffed herbaria, most of this material lay in storage until the 1950s, and some of it has only recently been examined in detail.  The collection was put together by three British collectors, but within it were materials collected by others, including at least one specimen of an Easter Island plant (see earlier post).  There were also specimens gathered by a German botanist Johannes Flügge (1775-1816) who established a botanical garden in Hamburg.  It was destroyed by Napoleon’s forces in 1813, yet here is a record of what was growing on the other side of the globe when New Zealand wasn’t even an official colony.  That’s the wonder of herbaria and why I study them.  I bore easily, but I am confident that there is an endless supply of examples like this to keep me intrigued.    


Harkness, D. E. (2007). The Jewel House: Elizabethan London and the Scientific Revolution. New Haven, CT: Yale University Press.

Moore, A. (2022). Grindelia ciliata (Astereae), Thomas Nuttall, and the exploration of the American West. Capitulum, 1(2). https://doi.org/10.53875/capitulum.01.2.07

Pedder-Smith, R. (2012). Herbarium Specimen Painting. Rachel Pedder-Smith. http://www.rachelpeddersmith.com/Herbarium/Herbarium.html

Spamer, E. (1998). Circumventing Captain Cook. Lewisia, 2, 2–5.

Spamer, E., & McCourt, R. (2002). The Lewis and Clark Herbarium of The Academy of Natural Sciences. Part 1. Notulae Naturae, 475, 1–46.

The Algal World: Diatoms


Diatom plate from Haeckel’s Art Forms in Nature

I was first attracted to diatoms by their exquisite beauty. When I studied aesthetics many years ago, beauty was often defined in terms of categories such as symmetry and form, and diatoms are definitely exemplars of both. They are one-celled algae, each encased in a glassy silica shell that varies with species. These structures can be elongated, triangular, circular, square, or more elaborately shaped. There is no better introduction to them than the diatom plate [shown above] from Ernst Haeckel’s Art Forms in Nature (1904). There are also great microscope photographs of diatoms on the web, at sites such as Micropolitan University. If you want more than just images, the Natural History Museum, London has Diatoms Online and the Academy of Natural Sciences (ANS) in Philadelphia (now part of Drexel University) has a Diatom Herbarium, both a real and a virtual space.

I visited the diatom collection at ANS two years ago and was drawn into a very different kind of herbarium world. Yes, there are metal cabinets, but they are filled with boxes of microscope slides, not sheets of white paper in folders. This collection was begun in the mid-19th century by members of the ANS who were interested in microscopy. At the time, this was, like seaweed, a hobby for many people who had the money to have leisure time and to buy a microscope. Some were physicians who had some familiarity with microscopes through their profession; others included bankers and industrialists who simply became fascinated with what couldn’t be seen with the naked eye. Like seaweed collecting, this was an area of interest in Britain, and also on the Continent, and had begun in the 17th century (Stafford, 1996). By the mid-19th century, microscope optics had improved and the instruments were easier to use. Many of the ANS microscopists were interested in fossilized diatoms found in diatomaceous earth, which could be found in areas around Philadelphia. This fine, sandy material is used in polishing among other things and represents the remains of organisms that lived in great numbers millions of years ago. Since diatoms are responsible for 20-25% of the earth’s carbon fixation, it’s difficult to overestimate their abundance, both now and in the past.

Eventually, the microscopists’ diatom collections morphed into the ANS Diatom Herbarium, which now houses the second largest such assemblage in the world. Along with slides, there are small glass bottles filled with diatomaceous earth collected in various locations. These are particularly difficult to catalog because each sample contains many species. In some cases, small portions of these sands have been separated out with individual species mounted on slides, but as Maria Popanova, the curator of the collection, notes the bottle that was the source of a particular mount wasn’t always recorded on the slide. There are ways of backtracking using dates and collection sites, but it’s time-consuming work and slows down digitization of the collection. However, 63,000 specimens are now available online. Also at ANS are rare 19th-century exsiccatae that contain many type specimens. These are store in book-like boxes with specimens either mounted on slides or in tiny envelopes. A counterpoint to these historically important items are posters on the walls of scanning electron microscope images of diatoms revealing an even more elaborate detail than that provided by a light microscope. The images are more expensive to produce so not every diatom receives this attention, but these images highlight the complexity of these minute structures.

I could easily dwell on the aesthetic aspects of these creatures, but I want to also stress their scientific significance. There are good reasons why the herbaria such as the ANS and NHS, among many others, maintain diatom collections. The cells can tell us a great deal about aquatic life of the past, the present, and the future. Diatoms serve as useful markers of aquatic ecosystem health. Their shells remain after death, providing stable evidence of water quality. A water sample’s use in monitoring usually deteriorates with time as organisms die, but this is a lesser problem with diatoms. Also, they are ubiquitous, found all over the world in both fresh and salt water. The species present at a site depend upon the presence or absence of pollution, among other factors.

Part of the research done at ANS involves water monitoring studies and having a rich diatom collection, including many type specimens, as reference adds weight to the findings. This work has a long history at the ANS, and the person most responsible for building its stature was Ruth Patrick (1907-2013). She had a doctorate based on diatom research from the University of Virginia and wanted to volunteer at the ANS in the 1930s. She was kept out for several years because they didn’t accept women. She finally became a volunteer in 1935, serving first as a virtual servant to the Microscopy Section, setting out specimens for their meetings among other duties. She eventually became the first woman member of the ANS. In the late 1940s, after she became a paid employee, Patrick founded the ANS Limnology Department. Through her work, the ANS developed a focus on freshwater diatoms; before that it had collected mostly fossils and saltwater species. She directed studies on rivers and streams, especially in terms of using diatoms to gauge water quality, and her influence lives on in the ANS’s Patrick Center for Environmental Research.


Haeckel, E. (1904). Art Forms in Nature (Vol. 1974 ed.). New York: Dover.

Stafford, B. M. (1996). Artful Science: Enlightenment Entertainment and the Eclipse of Visual Education. Cambridge, MA: The MIT Press.

Diatoms in the Herbarium

The diatom, Lyrella sp., photo from Fish and Wildlife Research Institute

The diatom, Lyrella sp., photo from Fish and Wildlife Research Institute

Diatoms are microscopic aquatic organisms that have glass-like shells.  These structures are symmetrical, and this symmetry combined with the transparency of the “glass” and the variety in their shapes makes them aesthetically awesome.  Their diversity and ubiquity in both fresh and saltwater environments also make them very important ecologically.  A few months ago, I visited the Diatom Herbarium at the Academy of Natural Sciences in Philadelphia, now part of Drexel University. Maria Potapova, the assistant curator in charge of the herbarium, gave me a tour and showed me some of the hundreds of thousands of specimens in the collection.  The usual metal herbarium cabinets are filled with box after box of glass microscope slides. In addition, there are vials and small bottles containing with the sandy remains of diatoms. Potapova explained why it is such a slow process to digitize the information about the specimens. A single vial may hold a number of diatom species, and individual species from these vials may have been mounted on a number of different slides. However, the links between slides and vials may not have been noted. Making these connections is possible through dates, collectors, etc., but it takes time.

Potapova also showed me several rare exsiccatae that contain many type specimens. The oldest, that of the German botanist Friedrich Traugott Kützing—Algarum Aquae Dulcis Germanicarum (1833-1836)—is in 16 notebooks with specimens wrapped in tiny paper envelopes or on glass. Another is the set of 22 small leather-bound book-like boxes filled with slides. The title on each spine is Diatomées de Belgique (1882-1885), and the collection was assembled by the Belgian botanist Henri Van Heurck. These are among the treasures of the collection, which includes specimens gathered in the 1800s by members of the ANS, many of whom were wealthy men who had microscopy as a hobby. The origins of the collection was in the Microscopical Society of Philadelphia, founded 1858. The first evidence of interest in diatoms at the ANS were three papers on marine and freshwater diatoms published by F.W. Lewis in 1860s. The Microscopical Society eventually merged with the Biological Section of the ANS to form the Biological and Microscopical Section.

Women could not become ANS members until well into the 20th century. In fact, Ruth Patrick (1907-2013), who had a doctorate based on diatom research at the University of Virginia, wanted to volunteer at the ANS but was kept out for several years. She finally become a volunteer in 1935, serving first as a virtual servant to the Section, setting out specimens for their meetings, among other duties. She eventually became the first woman member of the ANS. In the late 1940s, after she had become a paid employee, Patrick founded the ANS Limnology Department. Through her work, the ANS developed a focus on freshwater diatoms; before that it had collected mostly fossils and saltwater species. She directed studies of rivers and streams, especially in terms of using diatoms to gauge water quality. She collaborated with the noted ecologist Evelyn Hutchinson among others. Her influence lives on in the ANS’s Patrick Center for Environmental Research. Potapova and her associates continue to do both taxonomic and ecological studies on diatoms.  The importance of this work became evident when Potapova mentioned that diatoms are responsible for 20-25% of the earth’s organic carbon fixation.

The Nature Prints of Thomas Horsfield

Loranthus nature print from #625 in the Archives and Manuscripts Collection of the Academy of Natural Sciences of Drexel University

Loranthus nature print from #625 in the Archives and Manuscripts Collection of the Academy of Natural Sciences of Drexel University

Last summer, I visited the Academy of Natural Sciences in Philadelphia, which is now part of Drexel University.  Of course, I stopped in the gift shop, and I was drawn to note cards with nature prints on them: it was the delicacy of the prints that had caught me eye.  The information on the back indicated that they were from a volume of nature prints in the ANS Library.  They were done by Thomas Horsfield (1773-1859) in Java in the early part of the 19th century.  I didn’t have time to look at them that day, but several months later when I was again in Philadelphia, I made an appointment to see the prints.  Needless to say, the originals are even more impressive.  They are very fine, with all the veins and even flower forms carefully delineated.  In an effort to find out more Horsfield and the prints, I recently looked at a copy of the 1990 reprint of Horsfield’s Zoological Researches in Java and the Neighboring Islands; it includes a biographical essay on Horsfield by John Bastin, Emeritus Reader in the Modern History of South-East Asia at the University of London.

Horsfield was born in Pennsylvania, studied with a pharmacist, and then received a degree in medicine from the University of Pennsylvania.  He served as surgeon on a merchant vessel that sailed to Java, and when he returned home, he decided to go back to Java to study its natural history.  In 1801, he equipped himself and when in Java he gained support from the Dutch government for his explorations.  Because of his medical background, his main interest was in finding medically useful plants, but he collected widely and studied the geology of the region as well.  Over time, he became more and more interested in animals, especially after the British under Sir Thomas Stamford Raffles took over the administration of Java and Horsfield received support from the East India Company (EIC).

When he left Java in 1819, he went to England to continue his natural history work for the EIC.  He worked on his collections and eventually served as curator at the EIC’s museum.  By this time he had also gained the interest of Joseph Banks who was impressed by Horsfield’s plant collection and by the nature prints of over 400 plants that he had produced.  In an earlier letter to Raffles, Horsfield had explained that since herbarium specimens often rotted in the tropics he decided to make prints as a way to document plant features.  He applied ink to both sides of the specimen, folded a thin sheet of Chinese paper around it, and then burnished it.  This gave surprisingly good print of both sides.  In fact, Roderick Cave, the author of Nature Prints, writes that these are some of the best prints he has ever seen.  So there was a very good reason they caught my eye in the ANS gift shop.  There are three known copies of the prints, one at the Natural History Museum, London, one at the British Library, and the ANS volume, which was purchased by a Philadelphian and given to the library (Peck, 2014).

Horsfield, T. (1990). Zoological Researches in Java and the Neighboring Islands. Singapore: Oxford University Press.
Peck, R.M. (2014). Discovered in Philadelphia: A third set of Thomas Horsfield’s nature prints of plants from Java. Archives of Natural History, 41(1), 168-170.

Detail of Loranthus nature print from #625 in the Archives and Manuscripts Collection of the Academy of Natural Sciences of Drexel University