In the 19th century it was common to put more than one specimen on a sheet. Paper was expensive, and a small specimen didn’t seem to warrant all that space. In many cases, the two or even three specimens were from the same species but collected at different times and in different places. However, at times two different species were put together, making filing the sheet difficult. These problems faded in the 20th century, when good practices became more widely used. By this time, too, herbarium sheet size was regularized, though with some exceptions. The Natural History Museum, London and the Royal Botanic Gardens, Kew used different sized sheets, kept in different sized cabinets, which argued against plans many years ago to merge the collections. According to an agreement reached in 1961, the geographical collections of flowering plants were divided between the two and for the other specimens, Kew took on algae, lichens, and bryophytes, with NHM getting fungi and gymnosperms (Fortey, 2008). This led to a collective sigh of relief in both institutions since neither wanted to cede all their specimens to the other.
There have also been less formal agreements among herbaria worldwide, for example, to place the label in the lower right-hand corner of the sheet. Labels have gotten bigger as more information is considered essential. Not only species name, collector, place and date, but also collector number. It is now standard for collectors to keep track of their specimens by assigning a unique number to each and by listing the number and specimen name, perhaps with other information about the plant and where it was found, in a field notebook. These ancillary records have been invaluable in pinpointing the place of collection for older specimens with vague place information on the label (Canfield, 2011). Some herbaria also have the practice of putting an accession number for their institution, or at least identifying the institution on the label. There may be headings such as “Flora of . . .” to indicate that the plant was collected in a particular county, state, or country. The plant family name is often included, as well as information on who first described the plant, for example, Mimosa pudica L. for Linnaeus or Mimosa reduviosa Barneby, for the 20th-century American botanist Rupert Barneby.
Now it is common to also add latitude and longitude information, or GPS coordinates to pinpoint location. No wonder labels tend to be larger than they have been in the past. Some collectors describe the ecology of the collection site, giving data on the other species found with it or soil type or amount of moisture. One collector told me that his friends called his labels “Faulknerian” in their length and detail. In other words, he notes on the label what in the past would have probably ended up only in his field notebook. The advantage of this is that notebook and specimen can become separated from each other, especially because collections are usually made in multiples, unless it is a very rare plant. One specimen may remain with the collector and/or the home institution, while others are sent in trade to other collections, which in return send some of their specimens to the donors, thus broadening both institutions’ holdings.
Besides the plant itself and the label taking up “real estate” on the sheet, there may be other addenda. If the information on the sheet has been digitized, there will be a barcode to link it to the electronic record. If it has also been photographed or scanned, there will likely be an “Imaged” stamp, as well as a stamp for the institution owning the specimen. If an expert on the genera has studied the specimen after its original labeling, there will also be a “det.” or determination label with the name of the botanist, date of the observation, and perhaps a change in name if the expert considered it necessary. These are the most common decorations on a sheet, but there can also be drawings of portions of the plant especially flower parts, or a photograph of the living plant, or even a printed description or article attached to the sheet. The amount of ancillary information varies with institution and with collector, and idiosyncrasies are less common today than in the past. The Harvard botanist and orchid specialist Oakes Ames (1874-1950) had a large personal herbarium that he ultimately donated to Harvard. Many of his sheets include illustrations or copies of illustrations done by his wife, the artist, Blanche Ames (1878-1969). On some sheets, there are even watercolor sketches of live orchids (Flannery, 2012). Oakes Ames was also accustomed to adding photos and text, so his sheets are quite busy, with little white space left. They give a real sense of someone working with and on the specimen, and recording relevant information [see figure at the start of this post].
Collections I saw at the Manchester Museum Herbarium in Britain were also rich with additional material, sometimes requiring more than one sheet. While this might be seen as clutter that adds unnecessary bulk to folders, these addenda are also indications of how the collector, or those that followed, viewed the specimen in a larger context and wanted to enrich it with what they came to discover about it. These materials are part of a conversation on the plant extending over time. Every specimen is involved in such conversations, but they do not all have tangible reminders of the context in which they have been viewed and used.
Canfield, M. R. (Ed.). (2011). Field Notes on Science and Nature. Cambridge, MA: Harvard University Press.