On a Thursday night in the CSE, you will likely see students pacing around a room full of plant specimens as they mutter Latin names under their breath. These BIO 328 students are studying for professor Sarah Johnson’s weekly plant identification quiz, and the specimens they are memorizing represent many of the major species found throughout northern Wisconsin.
While local vegetative communities are studied extensively at Northland, there is little data about the region in Wisconsin’s online flora database. For this reason, Johnson has led an effort to digitize Northland’s herbarium, which will be added to the consortium of Wisconsin flora—a web page that includes samples from all around the state.
“Most of the submissions to the database are from Madison, or the southern part of the state in general,” Johnson said. “The north woods is underrepresented, and we have some great samples to contribute.”
Among the most notable samples collected from the region is a dragon’s mouth orchid collected near the south shore of Lake Superior in 1936; this is now considered a rare orchid in the state of Wisconsin.
This rare sample was collected by Newton Bobb, who was a member of Northland’s very first graduating class in 1908. He later returned as a professor to build a strong biology program at the College.
Although Bobb passed away in 1971, a great multitude of the samples now being digitized were collected by him. He also preserved many samples of fungus and rocks: specimens that are still used for educational purposes by professors today.
Digitizing data from long ago presents unique challenges like identifying the site where the plant was collected.
“Some of the samples pre-date our modern names for locations, so we have to get creative when determining where they’re from,” Johnson said. “One of Bobb’s samples, for example, is listed as coming from ‘Bad River Falls.’” Johnson speculates this is referring to what is now Copper Falls State Park.
To preserve a sample for future observation and study, botanists use a time tested tool called a plant press. The plant is laid out on a sheet of white paper, and arranged so that both the upper and lower surfaces of a leaf can be seen. Next, it is stacked with multiple layers of corrugated cardboard to allow for airflow before the whole stack is cinched down with small ratchet straps, flattening the plant and preserving it as a dried specimen.
Preserved plant tissue from centuries past can be very useful for advancements in botanical understanding; using samples from an herbarium, scientists found that leaves from one hundred years ago had a much higher density of stomata—microscopic openings on the leaf that allow for the exchange of gas. The decrease in stomatal density is likely due to a warmer climate, in which losing any water through this exchange is more costly for the plant. Pressed plant samples are also useful for identifying species and memorizing their scientific names, which are anything but stagnant.
“Latin names are now changing faster than ever as molecular biology reveals more information about species relationships,” Johnson said. “Some species we once thought to be related have turned out not to be, and vice versa.” When scientific plant names change following new discoveries, physical plant samples can verify whether or not a historical record is referencing the same species being studied today.
The digitization of Northland’s herbarium has been underway for several years, but there is still a long way to go. Piles of samples still lay unentered, many of which were collected by students of Jim Meeker, Johnson’s predecessor at the College. Meeker often had students collect “voucher samples,” verifying that an alleged species was indeed found at a site referenced in a project or publication. These days, Johnson is hesitant to send students out to collect physical samples.
“I’m afraid that students would over-collect certain species that we now expect to decline due to climate change,” Johnson said. “It’s likely that many students would travel to the same spots for collection, which could be a significant setback for populations living in the most accessible places.”
Despite a decrease in sample collections, current students still have many opportunities to get involved with Northland’s herbarium. Digitizing the collection is a top priority. Johnson is also encouraging students to record their findings on iNaturalist, a smartphone app that is georeferenced and user-reviewed.
“Physical samples are still extremely important,” Johnson said, “but the use of technology can help us strike a balance where we aren’t taking too many plants from the landscape.”