Widespread botanizing opportunities for rarest of the rare

Each year the Rare Plant Monitoring Program picks a plant deserving special survey attention. Monitors are not required to look for the target species but are encouraged to do so to build excitement and allow participants to become more familiar with that one plant. This year we will target not one but the 15 rarest plants on the Priority Rare Plants List. Doing so gives more people opportunities to survey for plants near where they live and also will provide important information as DNR gears up for coming assessments to determine if plants are to be added or removed from the state endangered and threatened species list.

Narrow-leaved vervain   Photo credit: Corey Raimond

Each of these 15 plants has only one population that meets the three criteria for Priority Rare Plants. (See page 4 of our 2017 program report.) They are truly the rarest of the rare. If you remember, this list is a subset of all rare plants known in Wisconsin. It includes rare plant populations that:

1. Have been seen since 1970
2. Have relatively precise locational information — usually known to within 40 acres
3. Found on protected, usually publicly accessible, land.

One of the most basic questions plant conservationists need to answer is how are the species we are interested in doing? In some cases, answering this question requires driving around the state, trying to visit as many populations as possible in a short survey window. In the case of these 15 plants, though, the results of one volunteer conducting one survey could help us answer this question. A single survey could find a thriving population or a couple plants barely hanging on. With one survey, a volunteer could identify impending hazards that threaten to wipe out the population if no action is taken. Our rarest species are our most vulnerable species, meaning they require close monitoring. Because they are so rare, though, it should be possible to collect really critical and valuable data on many species in a short amount of time.

How the data will be used

In the next few years the DNR will be updating the state Endangered and Threatened Species List. Understanding as much as we can about the rarest of our plant species will inform our decisions to move species from special concern to endangered or threatened status or downgrade species from endangered or threatened to special concern. Species also can be moved off the Endangered and Threatened Species List if we think they have been extirpated from the state. Given the rarity of these 15 species that is a real possibility.

The DNR will hopefully begin collecting more seed of rare plants in the near future with the goal of preserving our unique genotypes in long-term storage. These surveys for our rarest species could be reconnaissance for that future seed collection effort. Seed banking buys time by preserving genotypes while we develop a more comprehensive conservation strategy to address the threats responsible for species' decline. If we fail to collect these seeds, the unique genotypes found in Wisconsin will be vulnerable to winking out before we can preserve them.

Map showing last known sightings of 15 "rarest of the rare" plants targeted for special survey attention in 2020.

Left – Cooper's milkvetch (Anton Reznicek).   Right – Yellow wild indigo (R.W. Smith).

Name	State Status	Identification	Access	Last Observed	County
Striped maple (Acer pensylvanicum)	Special Concern	Easy	Moderate	1998	Door
Lobed spleenwort (Asplenium pinnatifidum)	Threatened	Easy	Moderate	1990	Iowa
Cooper's milkvetch (Astragalus neglectus)	Endangered	Easy	Moderate	2000	Door
Yellow wild indigo (Baptisia tinctoria)	Special Concern	Easy	Easy	1973	Columbia
Northwestern sticky aster (Canadanthus modestus)	Special Concern	Moderate	Moderate	2008	Douglas
Slender sedge (Carex gracilescens)	Special Concern	Difficult	Difficult	1977	Washington
Torrey's sedge (Carex torreyi)	Special Concern	Moderate	Easy	2009	Waukesha
Brook grass (Catabrosa aquatica)	Endangered	Difficult	Moderate	2001	Adams
Wolf's spikerush (Eleocharis wolfii)	Endangered	Difficult	Difficult	2003	Marinette
Mountain fir moss (Huperzia appressa)	Special Concern	Moderate	Difficult	1998	Bayfield
Silver bladderpod (Lesquerella ludoviciana)	Threatened	Easy	Difficult	1977	Pierce
Three-flowered melic grass (Melica nitens)	Special Concern	Difficult	Moderate	2012	Grant
Pale bulrush (Scirpus pallidus)	Special Concern	Difficult	Moderate	2004	Fond du Lac
Veined meadowrue (Thalictrum venulosum)	Special Concern	Easy	Easy	1997	Douglas
Narrow-leaved vervain (Verbena simplex)	Special Concern	Easy	Easy	2007	Marinette

Clockwise from top left: Lobed spleenwort (Thomas Meyer),   Slender sedge (UW Herbarium/Linda Curtis),   Silver bladderpod (Emmet Judziewicz),   Northwestern sticky aster (Scott Namestnik),   Striped maple (Kevin Doyle).