Just as William Starling Sullivant’s pasture introduced him to botany, a recent field trip to The Ohio State University’s West Campus taught me about a unique reference collection called a herbarium.
A herbarium is a collection of preserved plants that have been pressed, dried and mounted on sheets of heavy paper. Like an archive, it provides access to resources that have been arranged and described to facilitate information discovery.
While working as a librarian at the Ohio Historical Society’s Archives/Library, I saw my first example of a herbarium in the Evva Kenney Heath Papers (MSS 1274), a collection of correspondence, ephemera and photographs of an African-American teacher who later became a lawyer and was an activist for women’s rights. Evva’s brother, John, compiled a “Model Herbarium and Plant Record” in May 1895. Wandering the fields, thickets, gardens, woods and hillsides of Cardington, Ohio, John collected specimens of flowering plants such as violets, trilliums, Rue Anemone, Spring Beauty, English Strawberry, Sweet William, May Apple, Bloodroot, Heart Liverwort, Cranesbill, Jacob’s Ladder, Dutchman’s Breeches and Shepherd’s Purse. He arranged the specimens diagonally on the page, taping them in place. On the opposite page, he recorded the plant’s common and scientific names, as well as information about the specimen’s family, habitat, locality and collection date. A description of the specimen outlined details of the plant’s buds, roots, stems, leaves, flowers, fruit, seeds and other characteristics.
I thought about John Kenney’s plant record book during a recent visit to Ohio State’s Herbarium. After I saw some of the flowering plant specimens that William Starling Sullivant collected around Columbus in 1840, Mesfin Tadesse, the Herbarium’s curator of vascular plants, gave me a tour of the facility that is part of Ohio State’s Museum of Biological Diversity.
The Herbarium was founded by Dr. William A. Kellermann, Ohio State’s first professor of botany, in 1891. Today, its specimens are used in teaching students how to identify plants, mosses, lichens, fungi and molds. Researchers rely on them to study the evolution and natural relationships of plant species. Herbarium staff members employ them to provide the public with information about plants.
About a third of the Herbarium’s specimens represent Ohio vascular plants and another third represent plants from the remainder of the United States and Canada. The remaining third originate from other locales, obtained through gifts, purchases, exchanges with other institutions, and special expeditions to places like southern Africa, China and Korea. The Herbarium also serves as a depository for specimens of Ohio’s rare and endangered plant species that are collected and studied by botanists at the Ohio Department of Natural Resources.
Dr. Tadesse explained how the Herbarium’s collection of nearly 500,000 preserved specimens of over 420 types of vascular plants are housed and arranged in steel shelved storage cabinets. The specimens are color-coded for easy retrieval, following botanist Arthur Cronquist’s taxonomic system. In this system, flowering plant specimens are divided into two classes, with a number of subclasses, down to the family level, where each one is defined and described. Dr. Tadesse showed me how genus and species are kept alphabetically within each family and within each genus. Specimens are arranged geographically in colored folders: Manila for Ohio; green for North America, except Mexico and Ohio; orange for Mexico and northern South America; brown for Chile and Argentina; blue for northern Asia and Europe; yellow for India, Australia and New Zealand; gray for Africa and the Middle East; and salmon for cultivated plants in Ohio.
After Dr. Tadesse showed me how the vascular plant specimens are housed and organized, we peered into a portion of the Herbarium’s bryophyte (moss) and lichen collections, where specimens are stored in individual packets and arranged in alphabetical order. Fungi specimens are stored in packets affixed to herbarium sheets, while slime molds are mounted in the lids of small boxes and diatoms are attached to microscope slides.
We also checked out the Herbarium’s backlog of unprocessed specimens, stored between sheets of newspaper in more of those same color-coded folders, housed in more shelved steel cabinets.
Then, your ever-curious blogger asked how a specimen is preserved for inclusion in a herbarium. First, Dr. Tadesse explained, botanists collect specimens that best represent their population or show a wide range of variation. While in the field, they assign a number to the plant and record data like the date, locality, habitat, and other identifying details. To keep a voucher of what they saw, and to truly capture the flower, botanists also take a picture to accompany the specimen.
After the specimen is selected, it is washed and placed between sheets of absorbent blotter paper for drying, either with or without heat. For at least 24 hours, it is pressed between corrugated boards, creating a system for air circulation, until it is dry. Then the dried specimen is mounted to a 10 ½” by 16” sheet of heavy, acid-free paper for final pressing. It is arranged so that it best displays the plant’s characteristics, such as the arrangement and shape of flower parts and leaves. Large specimens are best arranged diagonally. After the specimen is displayed to its best advantage, it is adhered with Elmer’s glue to the paper. Then, small pieces of gummed linen tape are applied at intervals across the specimen to make sure that nothing is loose. For those specimens that glue might not hold completely, they are sewn in place with linen or cotton thread. A label bearing information about the specimen is traditionally placed on the bottom right corner of the sheet. The label includes such details as the name of the institution sponsoring the collection, the collector’s name, the collection date, the geographical area in which the specimen was collected, in gradually decreasing magnitude, the scientific name of the plant and descriptive notes about the specimen.
Since 2009, Ohio State’s Herbarium has been making its specimens more accessible by imaging them for inclusion in a database using BRAHMS, a software application for herbarium data management. The database contains entries for 170,000 Ohio vascular plant specimens. Online access to the database is available here. You can perform a quick search by taxonomic group or a more detailed search.
Since visiting the Herbarium, I’ve discovered fascinating facts about three historic herbaria. First, I learned that there was a herbarium at Biltmore, George Vanderbilt’s Asheville, North Carolina estate. Although it grew to contain more than 100,000 specimens, a flood on July 16, 1916 destroyed about three-fourths of the herbarium, and the surviving specimens were rehoused in what is now known as the Smithsonian Institution. Because so many duplicate specimens were exchanged in the years before the flood, many Biltmore Herbarium specimens can be found in various herbaria, including at Ohio State’s Herbarium. The Biltmore Nursery: A Botanical Legacy, by Bill Alexander, not only describes the Biltmore Herbarium, but also reproduces the 1912 Biltmore nursery catalog in its entirety.
Next, I paged through Herbarium of the Lewis & Clark Expedition: The Journals of the Lewis & Clark Expedition, Volume 12. Here, I learned that the majority of extant plants from the expedition are in the herbarium of the Academy of Natural Sciences of Philadelphia. Eleven are at the Royal Botanic Gardens, Kew and one is at the Charleston Museum. Meriwether Lewis collected, described and preserved all but one specimen of 177 species. These include plants with such terrific names as Raccoon Grape, Rancher’s Fiddleneck, Ragged Robin, Jeffrey’s shooting star, Field Horsetail, Old man’s whiskers, Pink Elephant, Buffaloberry, Needle-and-Thread, and Mountain Kittentails.
Finally, I soaked up the beautifully presented Emily Dickinson’s Herbarium: A Facsimile Edition. When the flower-loving author was a girl, she kept a herbarium in a blank book bound in what resembles ribbon-embossed cloth. She did not record the circumstances of how she collected her 424 specimens, but she did identify and arrange plants like Butterfly Weed, Climbing Bittersweet, Bedstraw Bellflower, Sheep’s Sorrel, Grass of Parnassus, Cardinal flower, Foamflower, One-flowered Cancer-Root, Gill-over-the-ground, Showy Lady’s-slipper, Clayton’s bedstraw, Robin’s plantain and Blue curls. Now, her herbarium is part of the Emily Dickinson Collection at Harvard University’s Houghton Library. In 2005, high-resolution digital color images were made of the binding, endleaves, and rectos of each leaf in the book.
To learn more about herbaria, I checked out the third edition of The Herbarium Handbook, edited by Diane Bridson and Leonard Forman and published by the Royal Botanic Gardens, Kew. A Guide to Herbarium Practice, by J.W. Franks, and Preparing Herbarium Specimens of Vascular Plants: Agriculture Information Bulletin No. 348, written by C. Earle Smith, Jr. for the United States Department of Agriculture, were other helpful resources.
For more about the Evva Kenney Heath Papers, track down a copy of the February-March 2001 issue of Echoes, the Ohio Historical Society’s member newsletter, and read the cover story, “Long Letters from a Short Life Leave Readers Spellbound.”
If you’re curious about Cronquist’s taxonomic system, see his books: The Evolution and Classification of Flowering Plants; An Integrated System of Classification of Flowering Plants; and Manual of Vascular Plants of Northeastern United States and Adjacent Canada.
If you’re interested in seeing Ohio State’s Herbarium, it holds an open house for the public in February. Researchers who would like to consult the collections can schedule an appointment throughout the year.