From the Lady Slipper Archive: The Genus Viola (Violaceae) The Violets

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. Wildflower Weekend 2025 will be at Carter Caves State Resort Park. Carter county is a hot spot of Violet (Viola) diversity in Kentucky, with 13 species of Viola found in the county. This article, from November 1992, is an in-depth look at the Violas of Kentucky. This article first appeared in Nov 1992, Vol. 7, No. 4. 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. 39, 2024, can be found.

The Genus Viola (Violaceae) The Violets

by Landon McKinney, KSNPC

There are approximately 40 to 50 species of wild violets occurring throughout North America. Of these, twenty-two species and several varieties occur in Kentucky. Virtually every wildflower enthusiast knows a violet when he or she sees one. Beyond that, distinctions between the various species become quite confusing on occasion, even for the seasoned professional.

Amateur botanists and wildflower enthusiasts alike may assume that the classification of these pretty, little herbs is complete and that there is no question as to what constitutes a species and what does not. However, this belief could not be further from the truth. The violets are considered by many professional botanists to be one of the most difficult groups of plants to work with when producing a floristic treatment.

This problem is certainly not unique to the violets, as many other groups of plants are known to be problematic. We all have had difficulties in identifying a particular plant at one time or another. The wild fact is that the science of taxonomy (the classification of organisms into like groups) is not an absolute science.

Why are the violets so problematic? Well, there are several reasons. One reason is that many species exhibit a wide range of variability in their supposedly definitive characteristics. For example, you find a particular violet and proceed to identify it based on the manual or wildflower guide that you are using. After making a tentative identification, you notice that the description says that the leaves are pubescent (hairy) but as you look at your violet, you see no hairs. Could this be another species, maybe one that is not included in the manual that you are using? Possibly, but a likelier explanation is that you just happened upon a particular plant that is exhibiting an extreme end to a natural range of variation, and that sometimes, this particular individual has few or even no hairs on its leaves. Another reason is that most species, when in close proximity to each other, hybridize freely, and the hybrids produced may be quite fertile.

Now that I have muddied up the water so to speak, let me attempt to make the identification of violets as simple as humanly possible. First, the violets may be divided based on whether they are stemless or stemmed (see figures 3 and 4). The stemless violets have all petioled leaf blades appearing from the base of the plant. The stemmed violets have aerial stems from which petioled leaf blades appear (several species will also produce leaf blades rising from the plant’s base). Second, they may be further divided as to flower color and this gives us the following broad categories:

  • wild pansies
  • stemmed blue violets
  • stemless blue violets
  • stemmed yellow violets
  • stemless yellow violets
  • stemmed white violets
  • stemless white violets

The wild pansies consist of two species (Viola rafinesquii and Viola arvensis). They normally occur in yards or in cultivated fields. Their flowers are quite pansy-like except that they are much smaller. They are quite similar to the garden variety called Johnny-jump-up (Viola tricolor).

The stemmed blue violets consist of three species including the long-spurred violet (Viola rostrata), the american dog violet (Viola conspersa), and Walter’s violet (Viola walteri). While infrequent, the first two may be found in rich, mesic, wooded situations throughout the eastern portion of the state while Walter’s violet is considered rare and only known from Jessamine, Fayette, and Carter counties. This violet prefers a limestone substrate and, due to its low-growing or decumbent habit, it is easily overlooked.

The stemless blue violets are probably the best known while also being the most problematic of the violets. The common blue violet (Viola sororia) is highly adaptable to a variety of habitats and we have seen several forms that adapt very well to our lawns and gardens. One of the most striking of these is the confederate violet with its grayish-blue flowers. Other stemless blue violets include the tri-lobed blue violet (Viola palmata), the arrow-leaved violet (Viola sagittata var. saggitata), the ovate- leaved violet (Viola sagittata var. ovata), the marsh blue violet (Viola cucullata), the southern wood violet (Viola hirsutula), Eggleston’s violet (Viola septemloba var. egglestonii), the Missouri blue violet (Viola sororia var. missouriensis), and the ever popular birdsfoot violet (Viola pedata). There are numerous other names of species that may be found in various manuals; however, these are either not found in the state or are now considered as minor variations of one of the above species.

The stemmed yellow violets include one of our most common woodland species, the smooth yellow violet (Viola pubescens var. eriocarpa). One unique characteristic of the smooth yellow violet is the fact that, after flowering, the seed capsules are either woolly or glabrous (hairless). I have never seen this character mixed in any one population as each population appears to have plants of one kind or the other. Nor have I ever been able to figure out, based on other characteristics such as habitat, which capsule type any given population will have. Another stemmed yellow violet considered rare in Kentucky is Viola tripartita, a woodland species known only from several counties in the eastern portion of the state. One of our prettiest violets is the halberd- leaved yellow violet (Viola hastata). While not always the case, the often mottled appearance of the leaf blades adds to the striking appearance of this species. It, too, is confined to rich, wooded situations in the eastern portion of the state.

We have only one stemless yellow violet. The round-leaved yellow violet (Viola rotundifolia) is confined to the eastern portion of the state and is our earliest blooming species. Its thick, leathery, rotund leaves lay prostrate on the ground and may be found in rich, wooded situations.

The stemmed white violets consist of two species, the Canada violet (Viola canadensis) confined to rich, wooded situations in the eastern half of the state, and the white violet (Viola striata), one of our more common species which seems to prefer alluvial or floodplain forests throughout the state. Although white flowered, Viola striata is more closely related to the stemmed blue violets than it is to the Canada violet.

The stemless white violets consist of three easily distinguished species such as the lance-leaved violet (Viola lanceolata) and primrose-leaved violet (Viola primulifolia), both of which love bogs, marshes, and wet meadow situations. The sweet white violet (Viola blanda), loves cool, moist, wooded situations and is mainly confined to the eastern portion of the state.

While being somewhat brief, I hope I have provided a greater understanding and a deeper appreciation for these lovely little herbs. The violets have a long history of use by man, especially in Europe. They are widely grown as ornamentals and our wild violets are used in a variety of ways as food. The leaves may be eaten raw and make an excellent nutritional addition to any fresh garden salad. The flowers may be candied for another delightful treat. Overall, the violets are quite an interesting group of plants and well deserve our attention and appreciation. Come next spring, take a closer look at these little herbs, appreciate their color, intrigue yourself with their subtle differences, and just enjoy. By the way, if you would like to see more than half of the above species in one day, plan a trip to Natural Bridge State Park next spring and walk the Rock Garden and Hood’s Branch trails. While these trails provide one of the best overall spring floral displays in the state, they also provide the only place that I know to see this many species of violets in such a short period of time.

From the Lady Slipper Archives: The Slender Lip Fern in Kentucky

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 year’s Fall Meeting will include a hike at Pine Creek Barrens Nature Preserve in Bullitt county. This article, from the fall of 2014, is about a rare species of fern, the slender lip fern, Myriopteris gracilis, found only in Kentucky in Bullitt county. The location of this fern is along Cedar Creek, in similar habitat to Pine Creek Barrens, and is about a mile away as the crow flies. This article first appeared in the fall of 2014, Vol. 29, 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. 39, 2024, can be found.

The Slender Lip Fern in Kentucky

by James Beck

A single low dolomite ledge near Cedar Creek in Bullitt County harbors one of the most unique plant populations in Kentucky. At a distance this might appear to be a population of the hairy lip fern, Myriopteris lanosa (Michx.) Grusz & Windham, a species known from >20 Kentucky counties. Most will probably know M. lanosa as Cheilanthes lanosa (Michx.) D.C. Eaton, a species recently transferred (along with most North and Central American species of Cheilanthes) to Myriopteris (Grusz and Windham 2013). However, closer inspection will reveal that these Bullitt Co. ferns have smaller, nearly beadlike ultimate segments that are densely hairy underneath, keying clearly to the slender lip fern, Myriopteris gracilis Fée (Cheilanthes feeii T. Moore), in either Jones (2005) or Cranfill (1980).

As the only known M. gracilis locality in the state, this small population would warrant considerable attention. Further investigation would reveal, however, that it is also one of three highly disjunct populations of this species in the eastern United States. The slender lip fern is widespread in the western and central U.S., common on calcareous rock outcrops from British Columbia south to northern Mexico, from southern California east to the Ozark Plateau and the upper Midwest’s “Driftless Zone” (Windham and Rabe 1993). The Bullitt Co. population, discovered by Clyde Reed in the early 1950s, represents a ca. 200 km disjunction from the nearest populations in southern Illinois (Reed 1952). The other two eastern disjunct populations are in southwestern Virgina (Wieboldt and Bentley 1982) and Durham Co., NC (Rothfels et al.

2012). These Kentucky, Virginia, and North Carolina populations add to what is already a remarkably large geographic range, a surprising level of geographic success considering that M. gracilis is exclusively asexual. The slender lip fern undergoes a modified meiosis that produces unreduced spores, which germinate and produce free-living unreduced gametophytes that then develop into adult sporophytes through mitosis. Because they bypass both recombination and the fusion of gametes, asexual species like M. gracilis are essentially genetically “frozen” line-ages, with minimal opportunity to create new genetic variation. Sex and recombination are traditionally thought of as necessary for maintaining the variation needed for adaptation, and asexual species are generally considered incapable of long-term evolutionary success. However, M. gracilis is one of a number of asexual species that occupy wider ranges than their sexual relatives. Although these big ranges could perhaps indicate success over shorter evolutionary time scales, they could simply be biogeographic illusions. As a polyploid (triploid), M. gracilis could have been derived from a sexual ancestor repeatedly over time. As a result, its broad dis-tribution could represent a single, successful lineage or a composite of several geographically smaller lineages formed at different times.

This research question is the focus of my graduate student David Wickell’s M.S. thesis at Wichita State University, and we have spent the 2013 and 2014 field seasons collecting M. gracilis across its wide range. That is what brought me to Cedar Creek this July – the chance to visit the disjunct Kentucky population and add it to our growing genetic dataset. On the long drive east from Wichita I prepared myself for disappointment, however. Although Reed noted that plants were “quite frequent” in his original publication, by 1980 Ray Cranfill noted only “three or four adult individuals.” These plants were presumably the ones observed and photographed by Richard Cassell and the Kentucky State Nature Preserves Commission’s Deborah White in 1994, although subsequent visits failed to relocate this population. On my visit I had the good fortune of working with KSNPC’s Tara Littlefield, and within 10 minutes she led me right to the plants! The population was healthy and sporulating but still quite small (nine adult individuals), and thorough searches of numerous nearby ledges failed to locate additional plants. Photos, geographic coordinates, and habitat notes were taken, along with a tiny amount of leaf material from one plant. DNA extracted from this material will be analyzed along with 94 samples from 20 states collected by myself, my student David, and several collaborators. From each plant we will obtain a kind of genomic “fingerprint,” and the relative genomic distinctiveness of each plant will allow us to determine how many lineages are found across M. gracilis‘ range. The logic is straightforward; individuals from the same lineage are asexual clones of one another and should be essentially genetically identical. On the other hand, individuals from different lineages should exhibit considerably higher levels of genomic distinctiveness. Data from our 95-individual dataset should clearly distinguish between the two alternatives discussed earlier: that of a single successful asexual lineage, or that of many restricted, less successful lineages. The status of the KY and VA (also visited in July) populations will be particular interest. Do these two populations represent the same asexual lineage, suggesting a sort of “stepping” stone colonization? Or do they belong to different lineages, suggesting that M. gracilis was once more widespread and diverse in eastern North America?

Whatever secrets M. gracilis holds, the opportunity to visit a truly unique piece of the Kentucky flora was one this native Kentuckian will remember. Special thanks go to the KSNPC for permission to conduct sampling, to Tara Littlefield (KSNPC) for showing me the site, and to Richard Cassell, Ray Cranfill, Ron Jones, and Deborah White for insightful correspondences

Cranfill, R. 1980. Ferns and Fern Allies of Kentucky. Kentucky State Nature Preserves Commis-sion Scientific and Technical Series, no. 1. 284 pgs.

Grusz, A.L., and M.D. Windham. 2013. Toward a monophyletic Cheilanthes: the resurrection and recircumscription of Myriopteris (Pteridaceae). PhytoKeys 32: 49-64.

Jones, R.L. 2005. Plant Life of Kentucky. The University Press of Kentucky. 834 pgs.

Reed, C.F. 1952. Notes on the ferns of Kentucky, III. Cheilanthes feei on Silurian limestone in Kentucky. American Fern Journal 42: 53-56.

Rothfels, C.J., E.M. Sigel, and M.D. Windham. 2012. Cheilanthes feei T. Moore (Pteridaceae) and Dryopteris erythrosora (D.C. Eaton) Kunze (Dryopteridaceae) new for the flora of North Carolina. American Fern Journal 102: 184-186.

Wieboldt, T.F., and S. Bentley. 1982. Cheilanthes feei new to Virginia. American Fern Journal 72: 76-78.

Native Spotlight: Turk’s cap lily (Lilium superbum)

By Robert Dunlap

In March 2022, I was lucky enough to find a new population of Turk’s cap lilies (Lilium superbum) containing about 500 stems in two colonies in McCracken County while searching for spring ephemerals. Additional searches yielded five more colonies containing another 1,700 individuals, all within about 75 yards of each other.

Due to my unfamiliarity with this plant and the lack of blooms, it took a little research to verify they were Turk’s cap lilies and not their close relative, Michigan lily (L. michiganense). Dichotomous keys usually differentiate between these plants using flower characteristics i.e., tepal curvature and anther length, which is not very helpful if you don’t have a flower to examine. Several online sources mentioned two vegetative characteristics to check: L. superbum has smooth leaf margins (not finely serrate), and the bulbs are white (not yellow). The plants I found exhibited both of these features so I’m going with the Turks cap lily. This plant was found by Mr. Raymond Athey less than 10 miles from this site in 1978, so there is historical evidence supporting the L. superbum identification, as well.

That being said, some botanists are reluctant to rely on the vegetative characteristics described above and feel that positive identification requires examination of flower structures. After being moved to more suitable sites in the future, my hope is that some of these bulbs will produce flowers allowing their identity to be determined beyond any doubt.

The species name is pronounced “superb – um” as opposed to “super – bum” and refers to the flowers, which can be translated from Latin as proud, superb, excellent, splendid, or magnificent. Mr. Linnaeus did a good job naming this plant back in 1762!

Ecology

Turk’s cap lilies are classified as threatened in Kentucky by the Office of Kentucky Nature Preserves and probably occur in less than a dozen counties. They are scattered across the state from Black Mountain in Harlan County in the east to Carlisle County in the west. Threatened plants are defined by the OKNP as “… likely to become endangered within the foreseeable future throughout all or a significant part of its range in Kentucky.” So, the assumption is that their numbers are declining and will continue to do so in the future.

Counties where Lilium superbum occurs in the U.S.

The BONAP map (Biota of North America Project) to the right displays the counties where Lilium superbum occurs in the U.S. Light green counties have stable populations while those highlighted in yellow have populations that are small and possibly declining.

It is generally more common in upland areas along the Appalachian Mountain chain, which includes Black Mountain. So how did they end up in McCracken County and across the Ohio River in southern Illinois? Some botanists have theorized that many southern plant species migrated north and west following the Cumberland River and the Tennessee River, which join up with the Ohio River near Paducah. Perhaps the lilies travelled from the mountains of North Carolina and Tennessee along these waterways over the last several thousand years or so.

Continue reading Native Spotlight: Turk’s cap lily (Lilium superbum) →

Successful buffalo clover establishment could require high seeding rates 

By Jonathan O. C. Kubesch*,**, Frank Reith*, Dillon P. Golding*,***, Jake Sanne*, Forrest Brown*,  Derek Hilfiker*, Joseph D. House****, Jenna Beville*, and Peter Arnold*,***** 

*Virginia Tech School of Plant and Environmental Sciences, Blacksburg, VA 

**Country Home Farms, Pembroke, VA 

***Hoot Owl Hollow Farm, Woodlawn, VA 

****Indiana National Guard, West Lafayette, IN 

*****Arnold Classic Farms, Chestertown, MD 

The public is familiar with red (Trifolium pratense) and white clover (Trifolium repens) growing throughout the Kentucky Commonwealth. However, North America, from Oregon to Florida, is home to a plethora of native clover species. Buffalo clover (Trifolium reflexum) is one of several clover species native to the eastern U.S.A. (Kubesch et al., 2022; Kubesch, 2020). This species demonstrates annual to short-lived perennial life histories, and has potential as a horticultural or agronomic crop (Quesenberry et al., 2003; Kubesch, 2020).  

Current efforts to increase native clover populations involve laudable efforts regarding site management, as well as conservation horticulture (e.g Littlefield, 2022). After a site is prepared for planting, plugs are produced. Conservation horticulture work currently executes the following procedure: 

  1. Germinate seeds on filter paper in petri dishes (Figure 1) 
  1. Transfer seedlings to cell pack trays 
  1. Pot up plants into small pots (Figure 2) 
  1. Plug individuals into spaced nurseries or maintain on benches for seed production 
Figure 1. Running buffalo clover (Trifolium stoloniferum) germinating on filter paper under laboratory conditions. Smyth Hall, Virginia Tech, Blacksburg, VA January 30, 2023. 
Figure 2. Running buffalo clover (Trifolium stoloniferum) growing in the greenhouse. University Greenhouses Bay 7A, Virginia Tech, Blacksburg, VA February 3, 2023. 

In restoration and agronomic contexts, seeding clover has a logistic and resource advantage over plugging clovers. Seeding clover can reduce the need for intensive planting efforts, reduce soil disturbance, and ease transportation of unique plant material. Seeding approaches require a basis for setting a seeding rate and dates. Often, clovers are timed for planting between Valentines’ Day and St. Patrick’s Day in the Upper South. Introduced red and white clovers are commonly frost seeded every several years into cool-season pastures (Kubesch et al., 2020). 

Seeding clovers can also take advantage of physiological mechanisms that improve seed establishment. In the field, frost seeding involves defoliation of an existing grassland stand, broadcasting clover seed onto the stand, and letting freeze-thaw cycles incorporate the seed into the soil surface. Compared to many native and introduced grasses, clover seed coats allow the seed to survive freeze-thaw incorporation into the soil surface. Quesenberry et al (2003) reports that buffalo clover has a similar seed weight to introduced clovers. A common rate of pasture frost seeding is 4 lb/A red clover and 2 lb/A white clover (Kubesch et al., 2020). 

Optimizing rather than maximizing seeding rate is desirable given the limited seed availability of buffalo clover as well as the desire to increase planting area in restoration attempts. Managers want to get a good stand with as little seed as necessary. In addition to generating stand densities that justify direct seeding over plugging, an optimal seeding rate should generate ground cover that conserves soil as well as meets existing criteria for composition.  

The present experiment sought to determine whether a 2 lb/A or a 4lb/A seeding rate can optimize buffalo clover establishment relative to white and red clover. This objective was measured through emergence as well as cover assessments. The hypothesis of this study was that the higher seeding rate will achieve the aforementioned targets comparable to, or greater than, red clover and white clover. 

Continue reading Successful buffalo clover establishment could require high seeding rates  →

Buffalo clover has moderate seed trait diversity across geographic range

Jake Sanne*, Dillon P. Golding**, Peter Arnold*, Jenna Beville*, Derek Hilfiker*, Forrest Brown*, and Jonathan O. C. Kubesch*, ***

*Virginia Tech School of Plant and Environmental Sciences

**Hoot Owl Hollow Farm, Woodlawn, VA

***Country Home Farms, Pembroke, VA

Introduction

Buffalo clover (Trifolium reflexum), is a rare native clover present in the eastern United States. In Kentucky, this species occurs in the vicinity of Mammoth Cave, as well as further west. Conservation efforts in the eastern United States have maintained many of these native populations, though there is interest in using horticulture and agriculture to increase buffalo clover populations (Quesenberry et al., 2003; Kubesch, 2020; Kubesch et al., 2022). 

A limitation of these alternative approaches is the lack of data regarding the establishment of native clovers. For many rare plants, plugs are grown in nurseries and then planted to field sites (Littlefield, 2022). Even in the only published horticultural research, seed was grown into plugs for field plantings (Quesenberry et al., 2003). Buffalo clover has a fair degree of phenotypic variability in growth form, life history, and flower color across the geographic range. These differences in plant material might also suggest diversity in seed characteristics. 

Seed weight is an important seed characteristic for increasing buffalo clover populations. Seed weights are associated with increased establishment success (Catano et al., 2022; Westoby, 1998). Published seed weights of red (Trifolium pratense), white (Trifolium repens), and buffalo clover come from a publication using buffalo clover accessions from the Coastal Plain (Quesenberry et al., 2003). Coastal Plain accessions appear to have annual life histories whereas Ohio River Valley accessions appear to be short-lived biennials or perennials (Kubesch, unpublished observations). The present study sought to map and determine seed weights for buffalo clover. The authors hypothesized that Coastal Plain accessions would have different seed weights than the Ohio River Valley accessions.  

Materials and Methods

This study consisted of a mapping exercise, seed weight data collection, and then analysis. The mapping exercise discerned the positions of Coastal Plain and Ohio River Valley accessions using the geographic Fall Line as the demarcation between Coastal Plain and Ohio River Valley accessions. Accessions found on the corresponding side of the Fall Line were assigned to a Coastal Plain or Ohio River Valley. This mapping was conducted in ARCGIS software.

Seed weight data for a handful of accessions was accessible from the USDA GRIN system. Notably, these seed weight data overrepresented Coastal accessions rather than Ohio River Valley accessions. Additional data came from Quesenberry et al (2003) as well as manual measurements. Quesenberry et al (2003) selected accessions from TX, GA, MS, and FL. One accession in this study came from the Ohio River Valley. Seed from single plant selections of Cincinnati and Clarks River accessions were measured on a lab balance (Bonvoisin scale). 

Data Analysis

Seed weight was treated as a completely randomized design. Initial analysis at the state-level was considered to address potential accession grouping at local scales. Differences in seed weight between accessions from the Coastal Plain and Ohio River Valley were also considered to test other known differences in accessions (e.g. annual or biennial life history). All analyses were conducted in SAS v9.4 (SAS Institute, Cary, NC). PROC GLIMMIX coded for a simple  one-way ANOVA.

Continue reading Buffalo clover has moderate seed trait diversity across geographic range →

Clarks Rivers NWR Buffalo Clover (Trifolium reflexum) evaluation and conservation

Jonathan O.C. Kubesch*, Kelly Winklelpleck*, Connor Doyle*, Lindsey Barbini*, John H. Fike*, and Michael Johnson**

*Virginia Tech School of Plant and Environmental Sciences

**Clarks River National Wildlife Refuge

Summary

Buffalo clover (Trifolium reflexum) is a true native clover of eastern U.S. provenance. Previous research suggests that buffalo clover has seed yields and weights similar to introduced clover species (making it suitable for increase). However, such research is limited, with little comparison of plant material from across the northern range of the species. In fact, there is overrepresentation of southern accessions from Georgia, Texas, Mississippi, and Florida. This overrepresentation stems from historical seed collections coming from Coastal Plain collections. In order to better represent accessions from the northern range of the species (both in current research and for future studies), this project sought to 1) conduct a comparison of buffalo clover accessions from across the range against red clover (T. pretense); and 2) bank seed from the Clarks River population for use in conservation and research. Plants were grown from seed to seed and studied in a common garden experiment with efforts taken to maintain genetic purity. Seed was then banked with the Southeastern Grasslands Initiative. Variability in phenotypes across the lifecycle were observed among northern and southern buffalo clover accessions, which suggests that the species complex has further structural variance. Southern accessions required less time to bloom and flowered without vernalization. Clarks River plant material has not yet flowered and appears to require vernalization.

Introduction

The native clovers of eastern North America are relics of the complex mosaic landscapes present prior to European settlement (Gillett and Taylor, 2001). Of these species, buffalo clover is an annual to biennial species with known morphological and reproductive variability (Vincent, 2001).

Kentucky clover (T. kentuckiense) is a recent addition to the flora (Chapel and Vincent, 2013). Species delimitation between Kentucky and buffalo clover has been determined using primarily floral characteristics; however, vegetative characters in a common garden experiment might further resolve the relationships within the species complex.

Previous work with Kentucky clover and running buffalo clover in greenhouse and field research suggest that these native species face fewer propagation challenges in comparison to other rare plants (Kubesch, 2018; Kubesch 2020). Historically, Dr. Norman Taylor at the University of Kentucky maintained all 3 clovers native to Kentucky in greenhouse collections (Kubesch, 2018; Daniel Boone, personal communication).

The objectives of this project were to collect seed from the northern edge of the buffalo clover range and compare buffalo to Kentucky clover. It was hypothesized that Kentucky clover would be more morphologically similar to buffalo clover accessions from Kentucky and Ohio than to accessions from the Coastal Plain.

Continue reading Clarks Rivers NWR Buffalo Clover (Trifolium reflexum) evaluation and conservation →

From the Lady Slipper Archives: Kentucky’s Common Milkweed (Asclepias syriaca L.)

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 Kentucky’s most widespread milkweed species, Common Milkweed (Asclepias syriaca), first appeared in the fall of 2011, Vol. 26, 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.

Kentucky’s Common Milkweed (Asclepias syriaca L.)
By David Taylor, US Forest Service

Whole plant with flowers

Common milkweed is a perennial forb that spreads by means of rhizomes and seed. It is one of about 115 species that occur in the Americas. Most species are tropical or arid land species. Plants may occur as a few individuals, but once established, form small to large colonies. Individual plants range from 1 to 2 m (~ 3 to 6 ft) tall. Leaves are elliptic to ovate to oblong and somewhat thick. Mature leaves are 15-20 cm (6-8 in) long and 5 to 9 cm (~ 2 to 3.6 in) wide, with a prominent midvein. The underside of the leaf is frequently finely pubescent. The stem is stout, usually simple, and green to black (see below) in color. When broken, the leaves, as well as stem and fruit, exude milky latex. Flowers are purplish to rosy pink to mostly white or even greenish and about 2 cm (0.75 in) long and 1 cm (0.4 in) wide. They occur in semi-spherical umbels (umbrella-like clusters) in the upper leaf axils. Flowers are somewhat complex in their structure, with structures not found in the average flower. The flowers are strongly and sweetly scented.

Milkweed pods

The fruits (pods), known as follicles, are formed from the union of multiple flowers. They are green, covered in soft spiky projections and are finely pubescent. When the seeds are mature, the follicle splits exposing the seeds. Each seed is equipped with a coma, a soft group of hairs. As the newly exposed seeds dry, the hairs of the coma expand allowing the seed to catch a ride on the wind. When broken, the leaves, as well as stem and fruit, exude milky latex.

Common milkweed is a widespread and somewhat weedy species. It is known from most of the eastern U.S and the eastern-most prairie states as well as southern Canada from New Brunswick to Saskatchewan. It is frequently found in fence rows, on roadsides, in fields, and in prairies and pastures. Given the opportunity, it will establish in gardens and even thin lawns. It is tolerant of light shade, but generally is a full sun species.

Monarch caterpillar on leaf

The genus name, Asclepias, commemorates Asklepios, the Greek god of medicine. Some of the species have a history of medicinal use including common milkweed (wart removal and lung diseases) and butterfly weed (aka pleurisy root— pleurisy and other lung disease). The specific epithet, syriaca, means ‘of Syria’ and is a misnomer: Linnaeus thought the species was native to Syria. This species is some times eaten as a salad herb, requiring multiple boilings of the young shoots before it is palatable. The reason for the boiling is to rid the shoots of various cardiac glucosides and other bitter principles. Milk weeds contain various levels of these compounds which render the plants toxic to most insects and animals. For some insects, the cardiac glucosides become a defense. They can store them in their tissue which renders them inedible or toxic to other animals. Monarch butterflies use this defense and birds leave them and the caterpillars alone. What the birds do not know is that northern monarchs feeding on common milkweed accumulate relatively little of the toxic compounds and probably would be edible. The more southern butterflies accumulate large amounts of the compounds from other species and are in fact toxic.

The stems contain a bast (inner ‘bark’) fiber used by Native Americans to produce twine and rope. The concentration and quality of the fiber make it potentially useful as a commercial fiber plant. Fiber quality is that of flax.

Common milkweed is an important pollinator and food plant for a large number of insects (more than 450 documented). It could be said that common milkweed is Nature’s mega food market for insects. Numerous butterflies, flies, bees, wasps, and beetles feed on the nectar and pollen produced by the flowers. Even hummingbirds will try, apparently unsuccessfully, to extract nectar. Aphids, especially the yellow-orange oleander or milkweed aphids (Aphis nerii), are commonly found on milkweeds including common milkweed. Large infestations of aphids can lead to formation of sooty mold on the plants which can turn the stems and leaves from green to gray to black. Two true bugs, the large milkweed bug (Oncopeltus fasciatus) and the small milkweed bug (Lygaeus kalmia) feed on the seeds, but the large milkweed bug is more often encountered. Large populations of either species can reduce the seed production potential of a colony of common milkweed by as much as 80-90%. The colorful (red with black dots) red milkweed beetle (Tetraopes tetraophthalmus) feeds on the leaves. The milkweed leaf beetle (Labidomera clivicollis), another orange-red and black beetle may feed on common milkweed but has a preference for swamp milkweed (A. incarnata). At least two caterpillars, the milkweed tussock caterpillar (Euchaetes egle) and the monarch butterfly (Danaus plexippus) feed on this plant. The red (or orange-red) and black coloration of most of these insects is known as aposematic coloration; that is, the colors advertise the fact that the organism is not good to eat. Other palatable species mimic the toxic species and gain some protection as a result. A well known example is the viceroy butterfly (Limenitis archippus) which mimics the monarch .

Large milkweed bugs
Predated milkweed seeds
Milkweed tussock moth caterpillars
Milkweed aphid, mothers and young, on Cynanchum laeve

For monarchs, common milkweed is among the most important food plants. It is the primary food plant for northern U.S. and southern Canada monarchs and is a major food plant for monarchs in the central and southern U.S. Monarchs migrating from the mountains of Mexico lay eggs on milkweed species in northern Mexico and the southern U.S. The butterflies that result from these eggs move further north in stages, with a change in species of milkweeds utilized as they move north. Common milkweed is the usual northern species. Monarchs can be helped by encouraging existing common patches of common milkweed and planting new ones. The plant grows readily from seed and spreads quickly by deep rhizomes. Because common milkweed can be weedy and difficult to remove, care should be used to establish the plant only in places where spread can be tolerated.