Unusual naturally occurring variant or escape from cultivation?

Lonicera sempervirens f. sulphurea, a yellow-flowered form of the red native honeysuckle

By Alicia Bosela, owner of Ironweed Native Plant Nursery

The native species of trumpet honeysuckle is a deciduous woody vine that typically grows to about 15 feet. It produces red tubular flowers with a yellow throat and is pollinated by hummingbirds and a variety of insects. Ornamental uses include trellises, fences and as a ground cover. Trumpet honeysuckle differs from native yellow honeysuckle (Lonicera flava) in that L. flava is not known to occur in Kentucky and has distinctly different shaped flowers. 

Yellow trumpet honeysuckle
Lonicera sempervirens f. sulphurea; Photo Credit A Fothergill
Lonicera sempervirens f. sulphurea , @ Tara Littlefield

While much of our wild flora is at risk from various human activity, the beautiful, red-flowered trumpet honeysuckle can still be found if one is doggedly persistent in searching. One such pursuer of native plants, Neville Crawford, located what was clearly a trumpet honeysuckle that was completely yellow and appeared to be growing in natural habitat within Mahr Park in Madisonville, Kentucky. John Swintosky, Senior Landscape Architect at Louisville Metro Public Works, discovered a yellow trumpet honeysuckle growing in Iroquois Park at least 15 years ago and confirmed its presence again in September 2021. This yellow form was reported in Iroquois Park in 1945 by P.A. Davies. Botanist Julian Campbell also encountered the yellow form in Boyle County, Kentucky.

Julian Campbell and Tara Littlefield under an arbor of the regular red trumpet honesuckle and the yellow variety that Julian collected from Boyle county, at Julian’s Botanical Garden in Lexington, Kentucky, May 2021. Photo by Christy Edwards.

Were these plants naturally occurring color variants of the red trumpet honeysuckle or an escape from cultivation? Britton and Brown’s Illustrated Flora of the Northern United States mentions the yellow form as early as 1913. The yellow form has been noted for sale in catalogues as early as 1938 and is likely “within the range of phenotypic plasticity for the species,” according to the New York Botanical Garden (personal communication). Therefore, this is almost certainly a natural yellow form of the typically red trumpet honeysuckle. How interesting!

Editor’s Note: You can see the yellow variety at Salato Native Wildlife Education in Frankfort, Kentucky at the headquarters of Kentucky Department of Fish & Wildlife Resources in the backyard exhibit.


Alicia Bosela owns Ironweed Native Plant Nursery in Columbia Kentucky, a certified woman-owned business. Before opening her own nursery, she was the Assistant Director of Clay Hill Memorial Forest Environmental Education Center. You can contact her at www.ironweednursery.com.

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** 
Not applicable* 
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. 

From the Lady Slipper Archives: Hydroleas (the genus False Fiddleleaf) in Kentucky – Lost and Found

The Lady Slipper newsletter of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. We occasionally feature an article from a past issue. This one, about one of Kentucky’s rarest genera, Hydrolea, first appeared in the fall of 2006, Vol. 21, No. 3. If you would like to see other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, No. 1, February 1986 to Vol. 34, No. 1, Winter/Spring 2019 (after which we moved to this blog format) can be found.

As a current update to this article, Hydrolea uniflora, the one-flower false fiddleleaf, was observed in full flower at Ballard Wildlife Management Area during the field trip there on July 31, 2021. Read about the field trip and see an image of H. uniflora at the article about the trip; Field Trip to Ballard WMA.


Hydroleas (the genus False Fiddleleaf) in Kentucky – Lost and Found

by Deb White

Hydrolea uniflora
photo from www.biosurvey.ou.edu

The two species of Hydrolea in the state have both been lost and found within the last few years! Both the ovate false fiddleleaf (Hydrolea ovata) and the one-flower false fiddleleaf (H. uniflora) were reported in the 1960’s to 80’s from several western counties. We had checked all the sites where these wetland plants were reported, and the sites appeared to be extirpated – for instance one had turned into a church. As soon as their ranks1 were changed to “Historic,” meaning they had not been reported for 20 years, they were both found in new places in western Kentucky. Robert Dunlap, a budding botanist and all-around naturalist, found a nice population of H. uniflora in Winford Wildlife Management Area. Julian Campbell reported that H. ovata is found at a wetland site within the Paducah city limits.

Hydrolea ovata
photo from www.biosurvey.ou.edu

These are both wetland herbs with blue flowers. H.uniflora forms a rooted mat of creeping decumbent (laying close to the ground rather than erect) stems in shallow open pools in wetlands. The plants are usually less than a foot tall if that and generally bloom in the late summer. H.ovata is much taller,up to 3-4 feet, when it blooms and hard to miss if in flower. It has little spines at the leaf axils and has many branches.

Both of these species occur along the edges of bottomland hardwood swamps and marshy openings in western Kentucky. They are distributed in the southeast United States and into Texas and Missouri. Kentucky is at the northern limit of their ranges, not surprising since this is generally a genus of warm climates.

The number of species that become historic and ultimately extinct in the state give us some insight into the rate of loss of our native flora. To date, Kentucky State Nature Preserves Commission lists 61 historic plants for the state. It is thrilling to find a plant that has not been seen for 20 years and re-assuring to know that the species continues to find its way in our changing world. In fact I am sure there is more Hydrolea out there to be found. If you are interested in knowing what rare plants, including those that are historic, occur in your area please visit our web site, Office of Kentucky Nature Preserves, and visit the Rare Plant Database for the listing for your county or to our rare plant website.

1 Each plant in the Kentucky flora receives a rank expressing its status in the state, from rare to common, historic or even extinct.


Update to the article:
As was mentioned in the introduction above, H. uniflora was observed during the KNPS field trip to Ballard WMA on July 31, 2021. Here are a few images of H. uniflora from that trip.

From the Lady Slipper Archives: Wild Bergamot – 2001 Wildflower of the Year

The Lady Slipper newsletter of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. We occasionally feature an article from a past issue. This one, about one of Kentucky’s loveliest natives, the Wild Bergamot, first appeared in the summer of 2001, Vol. 16, No. 2. If you would like to see other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, No. 1, February 1986 to Vol. 34, No. 1, Winter/Spring 2019 (after which we moved to this blog format) can be found.

The author, Mary Carol Cooper, left a huge legacy to the native plant community when she passed in 2016. In almost every native plant gathering, her name is mentioned and a moment is given over to appreciate her knowledge, which she freely shared. Her passion led many of us to our love of natives; she was a mentor and friend to many of us.

Wild Bergamot – 2001 Wildflower of the Year

by Mary Carol Cooper, Native Plant Program Coordinator, Salato Wildlife Education Center

Wild Bergamot (Monarda fistulosa) has been selected as the Salato Wildlife Education Center’s Wildflower of the year 2001 by wildflower enthusiasts from all across the state. The Wildflower of the Year is chosen based on the number of nominations it receives and how well it fits the established criteria (must be native, common and widespread across the state, seeds must be readily available, must be easy to grow, and must have wildlife value).

Wild Bergamot is common in old fields, thickets, prairies, and borders thoughout the state. It is a member of the mint family and has spicy-aromatic leaves that are opposite and ovate-lanceolate on a square stem. It has slender two-lipped corollas about one inch long densely aggregated in terminal clusters subtended by conspicuous bracts. The corolla is a pale lavender. Wild Bergamot ranges in height from three to five feet tall depending on the habitat. It is a short-lived perennial that rapidly forms colonies in both moist and dry soil. It is very versatile, as it will tolerate clay soils and drought and will grow in full or partial sun.

Wild Bergamot is a premiere nectar source for butterflies, moths, and hummingbirds. Indigo buntings are known to build their nests in the stems of this plant. It blooms from June through August, providing food and shelter all summer long.

Historically, physicians used leaf tea to expel worms and gas. The Native Americans used the leaf tea for colic, flatulence, colds, fevers, stomachaches, nosebleeds, insomnia, heart trouble; in measles to induce sweating, and poulticed leaves were used for headaches. The pioneers made a lotion of boiled leaves for treating pimples and skin eruptions. Today, Wild Bergamot is still used for headaches and fever and it makes a great tea. Its flavor is similar to true bergamot, the oil of a Mediterranean citrus fruit that flavors Earl Gray Tea. It is also excellent cut for fresh bouquets.

Hugh Wilson, Texas A&M Vascular Plant Image Gallery

Wild Bergamot seeds and plants are available from many native plant nurseries and are fairly inexpensive. It is also very easy to propagate either by seeds, cuttings, or division. Seeds sown in January should be kept moist and cold (40° F) for 90 days to cause germination. Since the seedlings are tiny and slow growing, they should remain in the flat for 6–7 weeks after germination before being transplanted. To propagate by cutting, take stem tip cuttings, 3–4 inches long, any time from May to August. Remove the lower leaves and all flower or seed heads, dip cutting in rooting powder and insert at least one node into a sand and perlite rooting medium. Place cuttings in an enclosed chamber and mist them several times a day. In 4–5 weeks, cuttings are well rooted and can be transferred to the garden in the early fall. To propagate by division, divide mature clumps in March before they send up stems. Dig up the plant and using a pair of pruning shears or a sharp shovel, cut the clump into sections. Replant and water the division immediately.

Native spotlight: Zizia aurea

By Susan Harkins

As the world begins to green up and spring ephemerals in the woods begin to fade, golden Alexander, Zizia aurea, lights up my yard. This rugged and easy-to-care for flower isn’t the first native to bloom, but it is the first to truly fulfill the promise of spring. Its delicate yellow sprays chase away the last of my winter doldrums because I know winter truly is over.

Golden Alexander, Zizia aurea

In your garden

Golden Alexander resembles Queen Anne ’s lace (Daucus carota) a bit, with their three- to four-inch-wide flat umbels of yellow blooms. However, they’re shorter at about 20 inches. As fall approaches, the capsule-shaped green seeds turn purple along with the foliage.

In nature, this perennial grows in meadows, woodlands, moist prairies, and along riverbanks throughout eastern Canada to the southern United States. They like a moist sunny spot, but they’ll tolerate some shade and dry summer soil. Because of their love for moist soil, they work well in a rain garden. They adapt easily and require little care. They’re a versatile little plant.

This bright flower lights up things so much that you’ll want to plant it in areas where you can easily see it from your windows, porches, and decks. If you have paths, put some around bends so they catch your eye as you wind through the spring green-up. You’ll enjoy an individual planting as well as clumps, and they make a eye-catching border in front of later-blooming natives. Their foliage and seed heads remain attractive throughout most of the summer. In fact, they will easily reseed if you don’t cut them back; once you see the seed heads, you won’t want to.

Consider pairing golden Alexander with wild geraniums (Geranium spp), smooth beard tongue (Penstemon laevigatus) , Ohio spiderwort (Tradescantia ohiensis) or wild columbine (Aquilegia canadensis). The colors, growth structure, and general size complement one another well. When planting in full sun, consider pairing it with short native grasses. If happy and left undisturbed, they will colonize after a few years.

Wildlife

Ladybug larva

Golden Alexander is a larval food plant for the black swallowtail butterfly (Papilio polyxenes). It’s also an important source of nectar and pollen for insects emerging from pupation and the early spring Azure butterfly (Celastrina). If you’re lucky enough to have lady bugs (Cycloneda) hibernate in your yard, you might find their eggs and larvae on the leaves—the latter is an interesting find! Native bees and wasps will appreciate both the flowers nectar and pollen. Birds love the seeds, so they’re a good choice for attracting birds into your yard.

Botany and pollination

Golden Alexander is a member of the Apiaceae, or carrot, family. If you let carrots go to seed in your vegetable garden, you might notice the family resemblance. Each flower has 5 sepals, 5 petals and 5 stamens. Flower clusters form a flat flower-head; the middle flower of each umbel is stalkless. Their sharply serrated compound leaves have three leaflets, in groups of three.

Pollination is best served by early spring pollinators with short mouthparts, such as bees, wasps, flies, and beetles. In addition, golden Alexander is self-pollinating.

Propagation

Seed capsules ripen over the season in the flat umbels. For most of the year they’re green, but slowly turn purple in the fall. Once they turn brown, they are ready to collect. They fall quickly once they’re ripe; they’ve usually fallen or been eaten by birds before I get to them. They are inexpensive to purchase if you fail to collect seeds, but you can always use the paper bag method to catch them. When sowing outside, do so in November after the first hard frost.

Seeds are tiny–less than a tenth of an inch.

Seeds require 90 days cold moist stratification at 40 degrees Fahrenheit. That can be a problem in Kentucky; the only month you can truly depend on is January. For that reason, I recommend the refrigerator stratification method. Seeds germinate best in cool soil, so put the stratified seeds outside early; they’ll be fine. Transplant seedings to pots in midsummer and then transfer to the yard in the fall. First year plants aren’t likely to produce blooms. As with most any plant, keep well watered after transplanting.

This native propagates from seed outside or inside easily enough although the germination rate may be low—plant a lot of seeds. Division works well, but the plants droop and look weary for a bit. Division can be successful if you have an established colony. Don’t divide plants for the first few years.

This carefree plant is flexible enough to grow in most yards. Their delightful delicate flowers shout “Spring!” Plant them all over your yard; you won’t regret it.

Native spotlight: Asclepias

By Susan Harkins

Thank you to Connie May, Jonathan Kubesch, and Nick Koenig for sharing their technical expertise on milkweed.

The monarch butterfly, Danaus plexippus is now a candidate species for the Endangered Species Act. Habitat loss and pesticide use along their migratory routes are responsible for the decline of the monarch, but you can help by providing habitat in your own yard. You’ll need two things: nectar for the adults and milkweed (Asclepias) foliage for their caterpillars. By planting both milkweed and other native wildflowers, my yard turns into a five-star resort for not only monarchs, but other butterflies and moths, beneficial insects, and birds.

Plant a patch of native wildflowers to attract adult butterflies and milkweed for their offspring. The monarch caterpillars eat only Asclepias. Kentucky Asclepias species that easily make the move to home gardens are:

Asclepias incarnataSwamp Milkweed
Asclepias tuberosesButterfly Weed
Asclepias verticillataWhorled Milkweed
Asclepias viridisGreen Milkweed
Asclepias syriacaCommon Milkweed
Swamp milkweed.
Photo by Betty Hall.

By planting both milkweed and other native wildflowers, my yard turns into a five-star resort for not only monarchs, but other butterflies and moths, beneficial insects, and birds.Despite its common name, swamp milkweed (Asclepias incarnata) will grow in most yards, though it will only reproduce reliably in wet spots. Be prepared to reseed or replant every few years to keep it going. Its deep-rose blooms are more spray-like than clusters and makes a stunning border for a larger area. It won’t spread to other areas, but it will fill in an area nicely.

Butterfly milkweed.
Photo by Betty Hall.

Butterfly weed (Asclepias tuberoses) has the most spectacular color—bright orange. It’s a bit bushy, grows 2 to 3 feet, and likes a sunny spot. It looks lovely planted with rue. Butterfly weed is the most dependable for returning in the same spot each year, but it doesn’t spread quickly. The leaves are thin, and I find few eggs or caterpillars on them, but the adult butterflies and other beneficial insects feed on the blooms. Butterfly weed blooms persist longer into the late summer than other milkweeds. Plant a few for a bright pop of color or create a spectacular border. Once they’re established, they’re very dependable.

Plant whorled milkweed (Asclepias verticillata) for fragrant blooms and interesting green foliage. It’s easy to establish from seedlings and like butterfly weed, whorled milkweed grows 2 to 3.

Of the five species reviewed, green milkweed (Asclepias. viridis) has proven the hardest for me to establish in a garden setting. It grows wild in every direction at my friend’s farm, so I keep trying. I encourage you to do so too because it’s so worth it! Its showy blooms are similar to common, but green, and the plants are shorter.

A monarch butterfly on common milkweed.
Photo by Betty Hall.

This article is about species that will work well in your home gardens. I don’t recommend that you plant common milkweed (Asclepias syriaca) in your yard. I include it to be comprehensive, but it’s beautiful in a big field far enough away that it doesn’t breech your landscaped yard.

In bloom, common milkweed is gorgeous and fragrant. Plant enough to cut some of those showy dusty-rose clustering blooms to bring inside because the scent is seductive. It prefers a sunny, well-drained spot and can reach seven feet. It spreads aggressively and dislikes intensive management. To be happy, plant it and plan to leave it be, keeping in mind that the caterpillars will completely defoliate it—another reason not to put it in your yard.

There are other species native to Kentucky, but these listed have proven most successful for me. I encourage you to explore the other species and experiment! The more you know about milkweed, the more successful your efforts will be. Common, swamp, and butterfly are readily found in nurseries in the spring. Seeds for all can be purchased online and at nurseries.

Continue reading Native spotlight: Asclepias

From the Lady Slipper Archives: Sweet Fern

The Lady Slipper newsletter of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. This is one of a series of reprints from past issues. This article, about sweet fern (Comptonia peregrina), first appeared in Vol. 26, No 1, Spring 2011. If you would like to see other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, No. 1, February 1986 to Vol. 35, 2020.

Sweet fern—A rare Kentucky shrub with an interesting history

By Tara Littlefield, Botanist, Kentucky State Nature Preserves Commission

Comptonia peregrine
Comptonia peregrine, KSNPC file photo

The wax myrtle or bayberry family (Myricaceae) is known for its odor. These plants have resinous dots on their leaves, making their leaves aromatic. Plants in this family have a wide distribution, including Africa, Asia, Europe, North America and South America, missing only from Australasia. Myricaceae members are mostly shrubs to small trees and often grow in xeric or swampy acidic soils. More familiar members of the wax myrtle family include many in the Genus Myrica (sweet gale, wax myrtle), some of which are used as ornamentals and are economically important. In addition, the wax coating on the fruit of several species of Myrica, has been used traditionally to make candles.

So what does this interesting family have in common with Kentucky’s flora? We are lucky to have just one species in the wax myrtle family, Sweet fern (Comptonia peregrina). In addition, it is also a monotypic genus restricted to eastern North America. This means that the genus Comptonia has only one species (C. peregrina) worldwide, and just happens to be found here in KY! Of course the common name sweet fern is misleading. This woody shrub is certainly not a fern. However, the leaves have a similar shape to pinnules of a fern frond (leaf). But having sweet in the common name is no mistake. If you crush the leaves throughout the growing season, a lovely smell is emitted as the essential oils volatilize into the air.

Female flowers (short round catkins with reddish bracts) and male flowers (elongated catkins clustered at the branch tips) – www.nativehaunts.comphenology.html

Sweet fern is a clonal shrub that grows up to one meter high and spreads through rhizomes. The leaves are alternate and simple, linear and coarsely irregularly toothed, dark green above and a bit paler below. It is monoecious (meaning male and female flowers on different plants). The female flowers are not showy— short rounded catkins [dense cluster of apetalous flowers, usually associated with oaks, birches and willows] with reddish bracts. The male flowers are elongated yellow-green catkins clustered at the branch tips, the pollen being adapted to wind dispersal. The fruit is a round, bur-like cluster of ovoid nutlets that turn brown when mature in late summer. The bark is reddish and highly lenticeled (small corky pores or narrow lines on the bark that allow for gas exchange).

While very common in the northern part of its range (northeastern United States and Canada), sweet fern is state listed endangered in Kentucky, along with being state listed as rare inOhio, Tennessee, South Carolina, West Virginia, Georgia, and North Carolina. The populations of sweet fern in the southern part of its range are isolated and disjunct from the common habitats up north. There seems to be a close association of these remnant populations with the Appalachian Mountains, which suggests that the populations in the southern ranges remained in protected “refugia” during periods of great plant migrations, such as during glaciations.

Sweet fern is typically found in openings in coniferous forests with well drained dry, acidic sandy or gravely soils with periodic disturbances. In the north, it can be found in pine-oak barrens or jack pine and spruce forests that are maintained by fire, creating openings and decreasing competition. It has also been noted to colonize road banks and even highly disturbed soils such as mined areas. Contrary to these open coniferous habitats with periodic fire, the remnant populations of sweet fern in Kentucky and Tennessee are found on sandstone cobble bars, which are maintained by annual floods. Despite being found on habitats that are maintained by different disturbance regimes, these two communities share a few things in common—they are both dry, acidic, sandy and nutrient poor. Disturbances are a natural occurring impact in these communities that removes shrubs and saplings, thus decreasing competition so that sweet fern can thrive.

Sweet fern has adapted to these specialized habitats. It is a fires adapted species; it will resprout after a fire and increase its clonal sprouts through underground rhizomes. It is also a xerophyte, a plant adapted to dry conditions. And since it is adapted to living in nutrient poor, acidic soils, it has evolved with the bacteria Frankia that fixes nitrogen, somewhat like the more famous nitrogen fixing legumes who have partnered with the bacteria Rhizobium. Did you know that there are over 160 species of nonleguminous plants that fix nitrogen? It is also the host of the sweet fern blister rust (Cronartium comptoniae) which reduces the growth of pines, particularly Jack pine. What interesting relationships this shrub has with bacteria and fungi! In addition, sweet fern is the food plant to larvae of many species of Lepidoptera (moths and butterflies). These include the Io moth (Automeris io), and several Coleophora case-bearers (some of which are found exclusively on sweet fern).

But perhaps the most fascinating facts about the rare shrub sweet fern is what it can tell us about the evolution of plants, the history of the earth, and the paleovegetational past of Kentucky. Geologically speaking, sweet fern is an old plant. In Kentucky, it was most likely more common some 20,000 years ago during the last glaciation, as Kentucky used to look like Canada. Analysis of pollen in sediment cores taken from natural ponds in Kentucky confirms this, spruce and jack pine was common in the uplands in the bluegrass. Sometimes it is difficult to think of plants migrating north and south in order to adapt to a changing climate. But what is even more mind blowing is that the genus Comptonia is perhaps millions of years old. Numerous fossils of dozens of extinct species of Comptonia have been found all across the Northern hemisphere, and the earliest of the fossils have been dated back to the Cretaceous period (the age of the Dinosaurs) over 65 million years ago. The first flowering plants (angiosperms) evolved only 135 million years ago, so Comptonia is one of the oldest living plants in the world—a true living fossil!

So when April comes around, and all of the spring wildflowers are emerging, think of sweet fern tucked deep into the gorges of Big South Fork and Rockcastle, its catkins releasing pollen in the wind, using the nitrogen fixed from its bacterial friends, withstanding the massive floods of two of Kentucky’s last wild rivers. And if you use your imagination, you may be able to see dinosaurs and tree ferns in the distance.

  1. Berry, Edward W. 1906. Living and Fossil Species of Comptonia. The American Naturalist. Vol. 40, No. 475, pp. 485-524.
  2. Darlington, Emlen. 1948. Notes on some North American Lepidoptera reared on Sweet Fern (Compontia asplenifolia Linnaeus) with Description of new species. Transactions of the American Entomological Society (1890-). Vol. 74, No. 3, pp. 173-185.
  3. Liag, X., Wilde, V., Ferguon, D., Kvacek, Z, Ablaev, A., Wang, Y., and Li, C. 2010. Comptonia naumannii (Myricaceae) from the early Miocene of Weichang, China, and the paleobiogeographical implication of the genus. Review of Paleobotany and Palynology. Vol. 163, p. 52-63.
  4. Medley, Max and Eugene Wofford. 1980. Thuja occidentalis L. and other noteworthy collections from the Big South Fork of the Cumberland River in McCreary County, Kentucky. Castanea. Vol. 45, No. 3, pp. 213-215.
  5. Natureserve Explorer, 2010.
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  6. Wilkins, Gary, Delcourt, Paul, Delcourt, Hazel, Harrison, Frederick, and Turner, Manson. 1991. Paleoecology of central Kentucky sicne the last glacial maximum. Quaternary Research. Vol. 36, Issue 2.
  7. Virginia Tech Woody Database
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  8. Zomlefer, W. 1994. Guide to Flowering Plant Families. University of NC Press, Chapel Hill.