Last year we targeted 15 of the rarest plants in Wisconsin for our Species of the Year search. This year we'll focus on the opposite end of the rarity spectrum: 12 species on the rare plant list that are relatively common. Visiting the lone population of a rare species can help us determine if the species should be removed from the State Endangered and Threatened Species List, or "delisted" because it is no longer present in the state. Searching for relatively common species, on the other hand, may provide enough evidence to downgrade a species from endangered to threatened or delist it entirely if it’s stable enough to persist without extra conservation attention.
Different from previous years, I encourage RPMP volunteers to search for and report new populations of these species. Since these plants are known from many locations, there are likely many populations yet to be reported. For example, putty root orchid (Aplectrum hyemale) is known from 65 locations in Wisconsin, but new populations are found each year. Many more populations of putty root are waiting to be discovered in the appropriate habitat — southern mesic and dry-mesic forests.
How do you search for a new population of a rare plant? First, you need to know where to look. The suitable habitat and the geographical location each plant is found in are included in the information about each species. The trick is to identify sites in those regions where the habitat occurs.
Some of these will be pretty easy. Seaside crowfoot, for example, is found along salted and mowed roadside ditches in the southeast and far northwest Wisconsin. Others, like Braun's holly fern, which is located in the rocky ravines in the Penokee Range, will be more difficult. For species found in a habitat that isn’t very common on the landscape, an excellent place to start might be state natural areas.
SNAs represent the best examples of the natural communities of Wisconsin and harbor a disproportionate number of rare species. You can find a list and description of each of the almost 700 SNAs by searching "state natural areas" from the DNR homepage.
Properties owned or managed by your local land trust are also good places to search for new rare plant populations. These sites may have been purchased recently and not had the thorough inventory older public lands have had.
Lastly, many volunteers know of private land with high-quality examples of natural communities and may support rare plants. Some of the species we are interested in, such as putty root orchid, white camas, dwarf milkweed, sweet colts-foot and seaside crowfoot can even hang on in degraded habitats, so private land that hasn't been managed in a while may still be suitable.
Of course, many searches for new populations of rare plants will turn up nothing. These species are rare, after all, which by definition means most sites do not have them.
Finding new populations of rare plants is daunting but exciting. Successes are rare, but each one represents a major advance in our understanding of the plants we're trying to protect. For the 12 Species of the Year in 2021, the picture is starting to suggest they are more secure than first thought. It would still be nice to get a few more puzzle pieces. We invite you to read the write-ups for each species and help us complete the puzzle by searching for one or more of them this summer.