Jeff Nelson in a field of tall goldenrod (Solidago altissima) in McCracken County.
As Fall winds down and the Winter Solstice fast approaches, this time of year is one of reflection and consideration of the year that is passing and the year to come. In 2026, the Kentucky Native Plant Society will be 40 years old. In 1986, several prominent botanists in the state came together to found a society dedicated to serving as a medium of fellowship and information exchange among botanists, both amateur and professional, to promote conservation of the native plants and natural plant communities of Kentucky, to promote public education in botanical science, and to encourage botanical research in Kentucky.
In the decades since it was founded, KNPS has grown to be a statewide organization of over 600 active members. It has introduced and educated thousands of Kentuckians to the importance and beauty of the state’s native plants and plant communities. Every year, more and more of our neighbors are planting native species for their beauty and, even more importantly, for their value to native butterflies, moths, bees, birds, and other wildlife. It seems that every week one hears or sees stories in the media about the native plant movement. We believe that the efforts of the Kentucky Native Plant Society, and native plant societies in other states, over the past 40 years have played no small part in this growth of interest in native plants.
Get ready and be observant on these cold mornings. We are now entering the time of year when we will begin seeing one of Nature’s loveliest and most evanescent phenomenons in our region; Frost Flowers.
What are Frost Flowers?
Frost flowers are thin ribbons of ice that form on the stems of a few species of native plants. Water from the roots is drawn up the stems (either as part of the plant’s natural transportation system or through capillary action) and expands as it freezes, breaking the stem walls and creating a flow of ice. As the ice forms, more water freezes, forcing out ribbons of thin ice . Other names for these structures are “ice flowers”, “ice ribbons”, “ice fringes”, “ice filaments”, and “rabbit ice”.
Conditions Needed for Frost Flowers to Form
Frost flowers form only when certain very specific conditions all come together:
Air temperatures must be below freezing (usually below 30°).
There should be little to no wind.
Ground temperatures must still be above freezing.
There must be some degree of soil moisture.
They only form on particular species of plants.
If conditions are right, the same plants can produce multiple frost flowers in a season, starting as early as November and producing frost flowers as late as early February. Usually the first frost flowers of the year will extend quite a ways up the stem, without extending out very far, as the entire stem splits. By the end of the season, when the stems are completely shredded, the frost flowers come out from the very base of the plant.
What Plants Produce Frost Flowers?
Worldwide, there are roughly 30 species of plants that produce frost flowers. In our region there are three native species that typically produce frost flowers. The two most common are white crownbeard, a.k.a. frostweed (Verbesina virginica) and common dittany (Cunila origanoides). A third species, that is mainly in wet areas, is marsh fleabane (Pluchea camphorata). I have heard that frost flowers sometimes appear on species of sage (Salvia) but I have never seen that and don’t know for sure what species of sage may produce frost flowers.
Frostweed (Verbesina virginica) Perennial herb, 3-7 ft. tall with winged stems. Leaves are alternate, broadly lanceolate, 4-8 in. long, with winged petioles. Flowers August – October
Dittany (Cunila origanoides) Semi-woody perennial, 12-18 in. tall with a strong odor. Leaves are opposite, oval, 1-1 1/2 in. long. Flowers August – October
Marsh Fleabane (Pluchea camphorata) Short lived perennial, 2-5 ft. tall with a camphor like odor. Leaves are alternate, broadly lanceolate, 3-10 in. long. Flowers August – September
Grow Your Own Frost Flowers
Although it is always exciting to find frost flowers in the “wild” another option for folks is to plant one of the natives that produce this phenomena in the yard. My frostweed patch came from a single plant that volunteered in the front yard about 6 years ago. It has reseeded itself and now many others have sprouted from the seeds of the original. On cold mornings I can now just look out the front window and see the frost flowers.
On Saturday, September 6th, KNPS members Steve Kistler and Carol Friendman led 16 participants on a rainy hike through prairie restoration areas in Mammoth Cave National Park. HIghlights included Cut-Leaf Prairie Dock (Silphium pinnatifida), Cup Plant (Silphium perfoliatum), Monkeyflower (Mimulus sp.), and Wingstem (Verbesina alternifolia). Participants also identified the birds, butterflies, and fungi in the area.
“Coming Together to Discuss Current Botany Projects, Conservation, and Collaboration in Kentucky and Beyond“
KNPS will be hosting our annual, virtual, Botanical Symposium on Monday, January 12th, from 9AM-1:00PM EST. For several years, KNPS has organized a botanical symposium in the fall/winter with a goal of bringing together professionals, citizen scientists, academics, gardeners and students in order to learn about what’s going on in the world of Kentucky Botany. Everyone interested in the native plants of Kentucky is welcome to watch the Symposium and there is no charge for this event. The Symposium will be recorded and will be made available online if you are unable to attend.
We are currently working on lining up presenters and developing the topics for the Symposium. Watch for the November Lady Slipper for the full agenda and for registration details.
The Symposium will include a slide show of updates from other individuals and organizations working with the native plants of Kentucky. If you or your organization would like to update Kentucky’s botanical community about recent native plant related news, projects, or upcoming events start planning your update now. When the Symposium registration opens in November, you will have the opportunity to upload a PowerPoint slide with your update.
Starting in 2021, the Kentucky Native Plant Society began formally recognizing individuals and organizations with the KNPS Conservation Award. Individuals and organizations are recognized for their outstanding contributions in advancing KNPS’s mission: to promote education about, appreciation for, and conservation of Kentucky’s native plants and native plant communities. When the Symposium registration opens in November, you will have the opportunity to submit nominations for the awards.
The day began in the Woodland Nature Center, located just beyond the state park lodge, with updates on the Society’s activities in 2025 and plans for 2026.
Dan and Judy Dourson shared personal experiences and read excerpts from their book Wildflowers and Ferns of Red River Gorge and the Greater Red River Basin. Afterwards, copies of the book were sold and the Doursons provided personalized messages and autographs. KNPS helped fund the 2025 reprint of Wildflowers and Ferns of RRG and GRRB and will have copies for sale at all future events while supplies last.
Following the updates the group enjoyed a talk by KNPS Vice-president and Office of Kentucky Nature Preserves Botanist, Kendall McDonald. She presented White Haired Goldenrod (Solidago albopilosa) and Sandstone Rockhouses of the Red River Gorge: Geology, Human History, Endemism and Conservation Success. Participants were also educated on the Adopt-A-Rockhouse Program, which is a program that utilitzes volunteers to monitor the previously federally listed White Haired Goldenrod (Solidago albopilosa, WHG). You can download the presentation by clicking on the image below.
The Lady Slipper newsletter, and now blog, 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. In this article from 2011, KNPS Board Member David Taylor, discusses one of Kentucky’s most widespread milkweed, common milkweed (Asclepias syriaca). This article ran in Vol. 26, No. 3. If you would like to see these and other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, February 1986 to Vol. 39, 2024, 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 (see Cut Flower Exports of Africa – Asclepias). The flowers are strongly and sweetly scented. 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.
On August 2nd & 3rd, 2025, Kentucky Native Plant Society enjoyed being part of the 29th annual Hummingbird Festival at the Woodlands Nature Station in the Land Between the Lakes, in Trigg County. For 29 years, the Hummingbird Fest has celebrated the beauty of hummingbirds, plants, and pollinators at the Woodlands Nature Station! With as many as two hundred hummingbirds a day passing through the Nature Station’s backyard, August is a great time to see the ruby-throated hummingbird.
Woodlands Nature Station staff, scientists, local artisans, native plant sellers, other conservation organizations, and KNPS had booths in the Nature Station’s backyard. Almost 2,000 visitors over 2 days came through to watch hummers and butterflies and other pollinators buzzing about the native gardens, got an up-close look at the hummingbird banding station, learned how to create habitat in their own backyard, shopped for native plants and avian inspired art, and enjoyed games and crafts with the kids!
