Mountain Lover (Paxistima canbyi) in Kentucky: Ancient flora, limestone outcrops, and Conservation Efforts

By: Tara Littlefield, Office of Kentucky Nature Preserves Botanist/Kentucky Plant Conservation Manager

  • Mountain lover (Paxistima canbyi) in Carter County, Kentucky (Photo by T. Littlefield)
  • Limestone outcrops/Mountain Lover habitat overlooking the Cumberland River in Pulaski County, Kentucky (Photo by T. Littlefield)

Mountain Lover (Paxistima canbyi) is a globally rare (G2), small evergreen shrub in the bittersweet family (Celastraceae).  This shrub is occurs in Kentucky (S2), Maryland (S1), Ohio (S1), Pennsylvania (S2), Tennessee (S1), Virginia (S2), and West Virginia (S2), and is listed as state threatened or endangered throughout its range.  This interesting shrub grows clonally and can form dense patches with stems reaching 6-12 inches.  Fruit development and seed production are reportedly quite rare in the wild and there may be fewer than sixty genetically distinct plants throughout its entire range due to its clonal nature, further compounding its rarity. 

One interesting note about the mountain lover is that it is thought to be an ancient glacial relict species, a remnant from a long lost ecosystem that occurred in this region prior to the last glaciation some 20,000 years ago. The late Dr. E. Lucy Braun, the esteemed plant ecologist from Cincinnati, had an interest in this plant and speculated that the mountain lover was an ancient glacial relict species that occurred along a pre glacial river system called the Teays River. I wonder how long these remnant populations have been clinging to the limestone cliffs and how old the root systems are of these clonal shrubs, perhaps thousands, even tens of thousands of years old?

  • Mountain lover has very small green/marron flowers with four sepals
    and four petals arising from upper leaf axils. While I occasionally see it flower, i have never found any fruits (photo by: T. Littlefield)
  • Global Range of Mountain Lover. http://bonap.net/MapGallery/County/Paxistima%20canbyi.png
  • Natural regions where mountain lover is found in Kentucky

I have long been fascinated by this plant and the limestone cliff and outcrop habitats where it grows.  In Kentucky, It occurs in several sub regions of the interior low and Appalachian plateaus, including the inner bluegrass, the knobs, and the cliff section/intersection of the eastern highland rim and Cumberland Plateau.  It is associated with limestone rocky ledges and cliffs, with an overstory/midstory of Chinkapin oak (Quercus muehlenbergia), Blue Ash (Fraxinus quadrandulata), Eastern Red cedar (Juniperus virginiana), and eastern hophornbeam (Ostrya virginiana).  The herbaceous/shrub layer includes shrubby st. johns wort (Hypericum prolificum), fragrant sumac (Rhus aromatica), smooth rockcress (Boechera laevigata), limestone cliff sedge  (Carex eburnia), purple cliff break fern (Pellaea atropurpurea), and wild columbine (Aquilegia canadensis).  The limestone cliffs and outcrops  typically occur in deep ravine gorges that form unique microclimates that also provide habitat for other glacial relict disjunct rare species such as Canada yew (Taxus canadensis), walter’s violet (Viola walteri), northern white cedar (Thuja occidentalis), glade phlox (Phlox bifida var. stellaria), purple oat grass (Schizachne purpurscens) and snow trillium (Trillium nivale).  The overall community assemblages of the mountain lover sites are unique between the various regions, and we are currently working with NatureServe to classify these plant communities to determine global rarity and classifications. 

  • Walters violet (Viola walteri, S1) grows with mountain lover in Carter county, KY, Photo: T. Littlefield
  • Canada yew (Taxus canadensis, S1), glacial relict disjunct rare plant grows with mountain lover in Carter county, KY, Photo: T. Littlefield
  • Gnarly Eastern red cedars (Juniperus virginiana) grow on the limestone cliffs/mountain lover habitat in Estill county, KY, Photo: T. Littlefield
  • Overlook at a mountain lover site in Estill county, KY, Photo: T. Littlefield
  • Northern White Cedar (Thuja occidentalis, S1), a glacial relict disjunct rare tree, grows with mountain lover in Wayne county, KY, Photo: T. Littlefield
  • View from below the limestone cliffs at a mountain lover site in Madison county, KY, Photo: T. Littlefield

Another common name of this plant is the “rat stripper” due to its relationship with eastern wood rats (Neotoma magister) that co-occur in the limestone outcrop habitats.  These animals have been known to sever the woody stems to utilize in nests building along the cliffs.  I have personally observed this phenomena at one of our Kentucky sites in Estill County, where I came upon a population with hundreds of freshly severed stems, wood rat tracks and nesting signs.  I collected a few of the fresh cut stems and rooted them in potting mix after that trip.  Could wood rats also play a role in expanding mountain lover populations along the cliff lines by inadvertently planting some as they drop stems along the cliff lines?

Major threats to the mountain lover include invasive plants such as bush honeysuckle (Lonicera maackii), Euonymus scale (Unaspis euonymi, a small non-native aphid-like bug), timber removal, deer browsing and climate change.  The majority of populations occur on private lands so development of the cliff tops has impacted a few populations and could be a threat to several more.  Perhaps the greatest threat in Kentucky appears to be from the Euonymus scale, with over 50% of our populations experiencing declines due to this nonnative bug.  Euonymus scale not only effects populations of mountain lover, but most species in the bittersweet family are affected as well, such as the eastern wahoo (Euonymus americana) and American bittersweet (Celastris americana).  Due to the steep, cliff habitat where mountain lover occurs, there could be undiscovered populations that are inaccessible to humans.   Additional surveys for new populations could further our understanding of the species and help evaluate its conservation status. 

  • Euonymus scale infestation on Mountain Lover population in Madison County, Kentucky. Photo by T. Littlefield. For more info on Euonymus scale visit https://entomology.ca.uky.edu/ef428
  • Medium infestation of Euonymous scale in a mountain lover population in Powell county, note yellowing of leaves, several dead patches were nearby, Photo by T. Littlefield

We know that mountain lover is globally rare, has numerous threats, and occurs primarily on private land.  So how can we work together to preserve this unique species? Conservation measures include networking with landowners that harbor mountain lover populations, targeting land acquisition projects to include these priority private sites, manage populations for the euonymus scale, and increase ex situ conservation efforts with horticulturalists.   In June of 2021, recent efforts by the Office of Kentucky Nature Preserves, Kentucky Plant Conservation Alliance, and the Atlanta Botanical Garden along with partners at the Daniel Boone National Forest, Berea College forest and several private landowners focused on visiting populations in all of the sub regions in Kentucky and collecting living samples to propagate for ex situ conservation and future introductions.  Site evaluations, natural community assessments and rare plant updates were also conducted as a part of this collection trip. Having additional sites on public lands would allow researchers and biologists more opportunities for monitoring and managing these populations into the future.   Conservation horticulturalist John Evans at the Atlanta Botanical Garden is now currently growing plants from 5 populations in Kentucky for future introductions within OKNP natural areas in the inner Bluegrass, Daniel Boone national Forest lands in the Cumberland Plateau, and Berea college forest sites in the knobs region.   

  • Calab Evans, Atlanta Botanical Garden Horticultural technician, roots cuttings of Mountain lover from recent collection trips
  • John Evans, conservation horticulturalist at Atlanta Botanical Garden, and Tara Littlefield, OKNP/KPCA botanist hanging out on limestone cliffs on a recent collection trip

If you would like to know more about these efforts or other Kentucky Plant Conservation Alliance efforts to conserve the rare plants and communities in Kentucky, please contact tara.littlefield@ky.gov.

Save the Date! Wildflower Weekend 2022

In anticipation of being able to hold in-person meetings again, KNPS would like you to save the date for Wildflower Weekend 2022. The next annual event will be held April 9th -10th 2022 at the Natural Bridge State Resort Park in Slade, Kentucky.

Save the Date! Fall Membership Meeting

Every year, KNPS hosts a fall membership meeting to discuss yearly updates and upcoming activities. This year, we will be hosting a virtual meeting via Zoom on Saturday, October 23rd at 4pm Eastern time. An agenda and full meeting information will be published in the October Lady Slipper. Please stay tuned if you would like to attend!

Delisting of Running Buffalo Clover

By: Heidi Braunreiter, Office of Kentucky Nature Preserves Plant Ecologist 

OKNP botanist conducting running buffalo clover survey in 2019 along Boone Creek in Clark County. Photo by Heidi Braunreiter.

Running Buffalo Clover (Trifolium stoloniferum) is a perennial clover with showy white flowers and leaves divided into three leaflets, and was historically native to several eastern and midwestern U.S. states. Based on numerous references to clovers in historical literature, it is believed to have been abundant across its historical range in pre-settlement times, which included the Bluegrass Region of Kentucky (Campbell et al. 1988). However by 1900, its extent had drastically reduced, and only five populations in total remained (Brooks, 1983). Throughout the 20th century, there were numerous fruitless attempts to relocate populations, which lead scientists to believe the species was extirpated from states where it was historically common. Finally, in 1983 populations were relocated in West Virginia and Indiana, as well as in northern Kentucky in 1987 (Campbell et al. 1988). With so few populations known, the U.S. Fish and Wildlife Service (USFWS) opted to list the species in 1987 as ‘federally endangered,’ because it was at a high risk of extinction (USWFS 2007).

The decline of running buffalo clover is believed to have been caused by a combination of factors: as land was settled, habitat destruction ensued and competition from non-native invasive species became a problem (Campbell et al. 1988). Another factor was the loss of the American Bison on the landscape. Historical observations noted the clover’s preference for sites where American Bison congregated (Bartgis 1985). Bison likely provided a means of fertilizer, seed scarification, seed dispersal, and the periodic disturbance regime necessary for the running buffalo clover’s life cycle (Campbell et al. 1988). The loss of bison from the landscape would have dramatically affected the species’ propagation.

Running buffalo clover in a cemetery in Boone County, Kentucky. Photo by Heidi Braunreiter.

Today, you will find running buffalo clover in areas that have periodical disturbances mimicking bison; for example, along trails where plants get trampled, in old estate lawns or cemeteries that are regularly mowed, and on stream terraces with occasional flooding events. Running buffalo clover also prefers dappled sunlight in a forested setting. If the forest canopy becomes either too closed or too open, running buffalo clover populations tend to decline in number as it does not tolerate full shade or full sun (USFWS 2021).

Over the past two decades, the Office of Kentucky Nature Preserves (OKNP) has conducted monitoring on running buffalo clover populations in Kentucky in order to look at population trends and manage for non-native invasive plants. Over this time, many new county records were discovered through targeted searches of historical estates, cemeteries, and stream restoration efforts in the Bluegrass Region. Several successful propagation and introductions efforts have also occurred over the years, for example, new populations were introduced and are now self-sufficient at Shaker Village at Pleasant Hill in Mercer County and Taylor Fork Ecological Area in Madison County.

In 2019, running buffalo clover was proposed for delisting by the USFWS, as many populations had been discovered since its initial listing over 30 years prior. In response to the 2019 proposed delisting, OKNP conducted a state-wide assessment of our running buffalo clover populations. Despite set-backs from the pandemic, we were able to survey 61 populations, which covered the majority of the known extant populations in Kentucky. Sites not included in the assessment were already determined to be extirpated, or inaccessible. Most populations in Kentucky occur on private lands, and although obtaining access to private lands can be difficult, we have been grateful for the curiosity, interest, and enthusiastic response from many property owners. Overall, population trends in Kentucky show approximately half of the populations as stable or increasing in size while the other half of populations are declining in size or extirpated (Table 1). Figure 1 shows an updated range map of extant running buffalo clover populations in Kentucky.

Table 1. Population trends of running buffalo clover in Kentucky during the 2019-2020 statewide survey. 

Population Trends Number of Populations 
Relatively stable  11  
Increased in size  18  
Decreased in size  21 
Extirpated** 9 
Not applicable* 2 
Total 61 

**Majority previously believed extirpated; extirpation confirmed 

* Previously uncounted; unable to compare trend 

A huge success that came out of the 2019-2020 statewide survey was the discovery of the largest running buffalo clover population in Kentucky. On the Mt. Folly Farm in Clark County, a population of over 6,000 plants was counted along the Upper Howards Creek. Other large populations of running buffalo clover in the state top out around 1,000 to 2,000 plants. The significance of this population led to the creation of a new Registered Natural Area with OKNP at Mt. Folly Farm. The clover occurs in the floodplain of the creek in cattle pastures and riparian woods. This site holds potential for future research as it has running buffalo clover in areas with and without a cattle-grazing regime.

As of September 2021, running buffalo clover was delisted by USFWS as they believe there are a sufficient number of populations occurring on publicly owned and managed lands to sustain the species’ viability (USWFS 2021). As of 2020, 175 extant populations occur across its range in Indiana, Kentucky, Missouri, Ohio, Pennsylvania and West Virginia, and biologists in these states discover new populations every year. Within Kentucky, many populations occur on Wildlife Management Areas where stream restoration projects are ongoing. The key to the future success of this plant is the continued management of populations to keep invasive plants at bay and the continued implementation of appropriate disturbance regimes, be that mowing, grazing, or trampling.

If you are interested in adopting a running buffalo clover population in Kentucky to do yearly checkups to remove invasive species, please contact me! heidi.braunreiter@ky.gov.  

Figure 1. Extant range of running buffalo clover in Kentucky as of February 2021. 

Bibliography 

Bartgis, R. 1985. Rediscovery of Trifolium stoloniferum Muhl. ex A. Eaton. Rhodora 87:425–429. 

Brooks, R. 1983. Trifolium stoloniferum, Running buffalo clover: Description, distribution, and current status. Rhodora 85:343–354. 

Campbell, J.J.N., M. Evans, M.E. Medley, and N.L. Taylor. 1988. Buffalo clovers in Kentucky (Trifolium stoloniferum and Trifolium reflexum) – Historical records, presettlement environment, rediscovery, endangered status, cultivation and chromosome number. Rhodora 90:399–418. 

USFWS. 2007. U.S. Fish & Wildlife Service: Running Buffalo Clover (Trifolium stoloniferum) Recovery Plan: First Revision. Department of the Interior, U. S. Fish and Wildlife Service, Great Lakes-Big Rivers Region (Region 3), Fort Snelling, MN. 

USFWS. 2021. U.S. Fish & Wildlife Service. Running Buffalo Clover Final Listing Determination Fact Sheet. https://www.fws.gov/midwest/endangered/plants/rbcl/runningb.html. Accessed 2 September 2021. 

Pine Creek Barrens Nature Preserve Field Trip

Kentucky Native Plant Society member Alan Abbott will be leading the second KNPS field trip since the start of the pandemic to Pine Creek Barrens Nature Preserve in Shepardsville. Owned by the Nature Conservancy, the 158-acre property was featured in Thomas Barnes’ book, Kentucky’s Last Great Places.

Pine Creek

This open woodland with a prairie-like ground cover hosts a diversity of native glade flora. Other natural communities at Pine Creek Barrens include the dry upland woods which surround the glade. On the southwest boundary, scenic Pine Creek flows through a beautiful mesic ravine forest lined with small limestone cliffs.

Barrens Silky Aster (Symphyotrichum pretense)

A number of rare or infrequent plants grow here, and most years, visitors can see Barrens Silky Aster (Symphyotrichum pretense), Great Plains Ladiestresses (Spiranthes magnicamporum), and Stiff Gentian (Gentianella quinquefolia) bloom in October.

At least eight rare and endangered plant species have been identified at the nature preserve, including the globally threatened glade cress (Leavenworthia exigua var. Laciniata), which has adapted to grow in small depressions on the exposed bedrock. This plant is found only in select areas in Bullitt and Jefferson counties.

Several years ago, KNPS adopted the policy of requiring preregistration for all activities (other than Wildflower Weekend) and for giving members the first opportunity to register for those activities. We send out emails to current members for all KNPS activities at least one week before the activity is announced to the general public. Participation in this trip was limited to 15 people and was quickly filled up by members. If you would like to get advance notification of future field trips, become a member of KNPS. If you join now, your membership will not expire until the end of 2022.

JOIN KNPS or RENEW YOUR MEMBERSHIP HERE.

First love

By Debra Parrish 

Ironweed, Vernonia gigantea. Photo credit: Theodore Webster, Common License.

August is time for the giants in the gardens to bloom. Of all the natives, these are my favorites and, ironweed was my first.

Your blooms mesmerized me and when I grew you,

your height fascinated me.

Farmers hate you. They can’t eradicate you with poison so,

they mow you down. A mere image of your true self.

You can be considered a bully. Nuisance is used

to describe you.

Not picky where you grow—fields,

pastures, roadsides, and in the urban garden at

the woodland edge. You are welcomed there, not a bully nor a nuisance.

Prevailing winds constantly at your back,

always standing tall.

The other giants with their issues,

requiring support, to stand tall.

Your presence reminds me year after year, how much

I love the colors of your blooms.

Intense in the sun; subdued in the shade.

Such a welcomed color amongst the other giants

in the urban garden.

You started the pursuit of always having your color

while yellow and white also still in bloom; from the beginning

of the garden season to the end; and, that love affair

started more than thirty-five years ago.

Perception—how it defines you. 

David Taylor, Forest Service

Tall ironweed, Vernonia gigantea, is a member of the sunflower family, Asteraceae. In Kentucky, plants begin blooming in August, occasionally, late July, with some individuals blooming as late as mid-October. The plant has alternate leaves each up to 10 inches long and 2.5 inches wide. Stems are typically 5-6 feet tall but can reach 9-10 feet in bottomland. The purple flowers are small, only about ¼ inch long, but because 20-25 are clustered together a head, and 50 to several hundred heads occur in one inflorescence, the plant is showy. Many species of small bees and butterflies will feed on the nectar produced by the flowers. A large plant can produce 1,000 or more wind-blown seeds.

Tall ironweed is a clumpy plant producing multiple stems from each root system, which is extensive and tough, firmly anchoring the plant in the ground. A few caterpillars and beetles eat the leaves, but otherwise the plant is relatively resistant to herbivory. Once established in a field, especially if overgrazed, the plant spreads quickly, aided by bare soil patches, and general immunity from grazing. The plant is difficult to eradicate and is generally controlled by mowing. In a garden setting, it is wise to cut the inflorescence off once the flowers are finished blooming if you don’t want them to spread. Dispose of the old flowers in the trash to prevent spreading of seed.

Debra Parrish lives in the heart of downtown and spends a lot of time and expends a great deal of love on her urban native gardens. She frequently offers summer tours for gardening clubs and other native gardening organizations.

KNPS Announces 2021 Fall Research Grants for Students and Citizen Scientists!

Did you know that the Kentucky Native Plant Society offers small grants to help defer the costs of botanical research, inventory and native plant restoration? Since 2012, KNPS has awarded $8,100 to students working in these areas. Another $750 was awarded in prior years. The total number of grants awarded in any given year is based on the number of proposals received, the quality of proposals and available funding. The graph below shows the kinds of projects that have been funded.

The second type of grant is new and is open to anyone. It will fund

1.  native plant inventory, or

2.  rare and native plant restoration.

Native plant inventory grants are limited to Kentucky locations and successful applicants will receive a maximum of $250. Rare and native plant restoration grants are awarded to applicants working with native Kentucky plants, preferentially those which are globally rare (G1, G2). Successful applicants will be awarded a maximum of $500. All rare and native plant restoration grants require coordination with the Office of Kentucky Nature Preserves (OKNP) and the Kentucky Native Plant Conservation Alliance coordinators prior to application.

A grant proposal must include:

  1. A current curriculum vitae;
  2. A proposal (not to exceed two single-spaced typed pages) describing the proposed research and the role the grant would play in the research;
  3. An itemized budget;
  4. A letter of recommendation from the applicant’s major professor or project director; and
  5. Indicate whether the grant request is for a student research grant, a native plant inventory grant or a rare and native plant restoration grant.
  6. If the grant is for rare and native plant restoration, include a letter of support from OKNP.

Budget items typically funded include travel to research sites and supplies such as herbarium paper and lab consumables. No personnel time will be funded.

All Grant Proposals are due by October 15, 2021.

If you are interested in applying for any of the KNPS grants, visit the Grants page at the KNPS website. If, after reading the grants page, you have any questions, please email them to: grants@knps.org.