Dr. James R. Carter, Professor Emeritus
Illinois State University, Normal IL 61790-4400
In a process called Ice Segregation cold water moves through a medium toward the presence of ice, freezes at the interface and adds to the ice. Ice Flowers and Frost Flowers are the most common names for the growth of ice on plants stems through the process of ice segregation.
Ice segregation occurs in many places at the surface of the Earth where we have freezing and thawing. When this occurs on some pieces of dead wood in the presence of some types of fungi, we see Hair Ice . When this occurs at or near the surface of soil it produces Needle Ice, which takes the form of strands of ice rising vertical from the surface or near surface of the soil. And, it has been found that ice segregation works through small rocks to produce what is called Pebble Ice . This author shows his Ice Segregation Garden where the four types of ice occurred in close juxtaposition.
Ice Segregation is also known to occur in subsurface environments and can be a significant geologic force in areas with permafrost and in periglacial environments.
On the Names of these Ice Formations and the Plants
Dr. Bruce Means was the first person in current times to publish broadly on these ice formations on plants and calls them Ice Flowers . Some of the plants which support such growths of ice are called frostweed and some call the ice formations Frost Flowers. Many people who find such growths of ice often give them names that are descriptive of what they see. In addition to Ice Flowers and Frost Flowers you may see names such as Ice Ribbons, Ice Fringes, Ice Filaments, Rabbit Ice, Ice Castles, Frost Castles, Ice Leaf and Eisblatt. Dr. Robert Harms has proposed the name Crystallofolia based on Latin roots - basically translated as Ice Flower.
Although often called Frost Flowers it should be noted the formation of this ice is NOT a deposit of frost. But many photos of Ice Flowers show that frost has occurred nearby, and in some cases, frost is deposited on the Ice Flower. It should be noted Dr. Forrest Mims III used the name Frost Flower in his online video showing the growth and display of such ice.
There is no agreement nor authority to decide what these beauties of nature should be called. This has led to confusion in the media where someone has referenced a formation of ice that they were not personally familiar with. Similar names have been used for growths of ice on windows, on plant stems and in the waters of the Arctic and Antarctic. I try to resolve this confusion on the page: Frost Flowers: One Name, Two Different Things.
There are only a few plants that have been identified with the formation of this type of ice. White Crownbeard or Frostweed, Verbesina virginica, and Common Dittany, Cunila origanoides, are the two most common native plants that produce Ice Flowers in North America. A few other plants produce such ice forms under the proper conditions. Carter has compiled a list of flowers reported to have produced Ice Flowers. However, this list is not definitive and now that more persons are learning about the products of ice segregation, we should expect that persons will find other plants that produce similar ice and inform us of these findings.
I found ice on a number of plants, including the ornamental Penta. The ice on the stems of Penta is quite different from the images shown here. I created page showing Penta ice and Ice Flowers I have been able to grow in a freezer.
Descriptions from the Past
In 1988 Lawler published a bibliography of Needle Ice listing 267 references dating back to 1824. Within these many references are citations that definitely refer to what are Ice Flowers.
One of these citations was the letter of J. F. W. Herschel dated January 12, 1833, in Philosophical Magazine, 3rd series, 110-111, entitled: "Notice of a remarkable Deposition of Ice around the decaying Stems of Vegetables during Frost." He wrote that years before he had found ice ". . . to incrust the stalks in a singular manner in voluminous friable masses, which looked as if they had been squeezed, while soft, through cracks in the stems." Then on January 11 he found a similar formation of ice which he described as ". . . seemed to emanate in a kind of riband- or frill-shaped wavy excrescence, -- as if protruded in a soft state from the interior of the stem, from longitudinal fissures in its sides, . . . the structure of the ribands was fibrous, like that of the fibrous variety of gypsum, presenting a glossy silky surface"
So, there is nothing new about Ice Flowers, but we now have digital cameras to capture such blooms and the Internet to share our findings.
Ice Flowers of Various Sizes in Various Places
I found my first Ice Flowers in 2003 and found the three forms of ice in Virginia in 2005. I have yet to identify the plant on which that ice grew in Virginia. Is it a Boneset?
Once I became aware of Ice Flowers, I found seeds of Verbesina to grow ice where I live. It is much easier to find and monitor the behavior of the plants if they are nearby. After two or three years I found I had two varieties of Verbesina - virginica and alternifolia. The big differences are virginica has white blossoms and grows ice and alternifolia has yellow blossoms and does not grow ice. Kurz states Verbesina virginica is known as White Crownbeard and Frostweed while Verbesina alternifolia is known as Yellow Ironweed. I now know there are two other varieties of Verbesina and neither of these produce ice flowers: helianthoides and occidentalis, both with yellow flowers. The Verbesinas have a single, straight stalk with four wings along the stem. They can be quite tall.
Early in one season I found two small growths of ice on stems of green Verbesina virginica. The only other evidence of freezing conditions on that calm morning was frost on a windshield of a nearby car. The ground was too warm to have frost on the grass so within a small elevation range the temperatures were cold enough to induce the process of ice segregation.
Figure 3 - The two Ice Flowers above are about 3 cm (1.2 in.) long. They are about 10 cm (4 in.) above the ground surface. The plant is Verbesina virginica, with a hairy stem and wings along the stem. While it is tempting to consider plant form as a factor in producing Ice Flowers, the other Verbesinas have hairy stems with wings but they do not produce Ice Flowers.
Later in the season the growth of ice becomes more common and produces larger blossoms, as in the example below. Note that here the stems are still green.
The example below shows a very complex Ice Flower from probably more than one stem of Verbesina virginica, White Crownbeard. In this case the stems are not visible.
I am not able to say if these differences in the appearance of the ice is due to the length of time the temperatures were below freezing each day or if the nature of the stems evolves as ice forms on the stem time after time. I do know that at the start of the season ice forms quite high up on the stem and may extend all the way to the ground. I have seen ice extend 75 cm (30 in.) up a stem. As the season progresses the ice does not extend as far up the stem.
The most voluminous formations of ice generally occur two to four weeks after the first formations of ice flowers and occur at or near the ground. The later dates are probably because the temperatures are below freezing for a longer time, but perhaps the stems have been transformed by previous growths of ice.
Ice Flowers on other Plants
The first Ice Flowers I saw were on Dittany Cunila origanoides in Tennessee. Subsequently I saw most of my ice on Verbesina virginica, and that is what I was able to get and grow in my yard. Most of the emails I receive from others show Ice Flowers on Verbesina virginica.
Dr. LeConte in 1850 noted the ice he saw was on Pluchea. Pluchea odorata Marsh Fleabane is one of two plants where Dr. Robert Harms finds Crystallofolia - in Texas.
I have received emails from many persons who have seen Ice Flowers on other plants, many ornamentals in their yards. And, some Europeans have sent me information on what they have observed. I have compiled a listing of all plants on which persons have reported seeing Ice Flowers.
The first season I had stems of Verbesina in my yard we found ice growing on an ornamental flower. This was on a stem of Red Salvia, a cultivar. The ice was not very attractive, but it was an Ice Flower on a plant stem. Surely, it was not the first time ice had grown on a plant stem in my yard but it was the first time I had looked at my yard in that way. Now I look at plant stems everywhere on mornings when it has been above freezing and the temperature has dropped below freezing. And, I continue to plant that basic Salvia in red, white and purple and enjoy the good ice flowers it produces.
I started planting a variety of ornamentals in my yard to see what happens.
The photo on the left in Figure 1 above shows the first Ice I ever saw, on Dittany Cunila origanoides. It is a relatively small, fine-textured shrub with small, purple flowers, much different from the tall, single-stem Verbesinas. I purchased seeds and plants and have Dittany in my yard.
The ice on Dittany appears in only one or two sheets along the stems. And, it may produce ice many times throughout the cold season. The photo below shows the relative size of the ice, with a wave in the ribbon of ice and some dry flower buds above the pebble. Then to my surprise I found that on a March 6 ice was growing on the residual stem from last summer while new plants were emerging as red shoots of new growth. This has occurred many mornings in the early spring.
On rare occasion I get a report from someone who has found Ice Flowers on Dittany in nature. I have purchased my Dittany from Missouri Wildflowers.
In fall 2014 I found ample growths of ice on five Penta plants in my yard. And, this ice is significantly different from that on other plants discussed here. Plus, I found I could grow ice on plant stems in a refrigerator using the same process I used to produce Pebble Ice. So, I put a new page together showing my ice on Pentas in the yard and in the refrigerator.
In 1933 Libbey wrote about Ice Flowers in Crater Lake National Park in southern Oregon. But, I have not heard of Ice Flowers in the humid Pacific Northwest although there are many reports of Hair Ice , a related product of ice segregation. Libbey compared the ice flowers to those found on Dittany back east but did not say on what plants this ice formed on in the Park. She did note that in some cases the ice flowers formed on broken stems sticking out of the water.
I have seen two photographs from persons who found Ice Flowers in the Himalaya of northern India. And, persons in Switzerland who knew about my interest found Ice Flowers on a variety of plant stems and shared photos of them with me. I suspect they occur in many more places than I have heard about because the climatic conditions with necessary freeze and thaw cycles are common in many parts of the world.
Ice Flowers in Poems
In addition to photos and descriptions of ice flowers, Ingrid Karklins in Austin, Texas, found inspiration to write a poem, entitled Verbesina virginica.
In Queensland, Australia, an elementary school teacher had her students learn about science by writing poetry. Ten-year-old Evie found my web pages on Ice Flowers and those photos gave her the inspiration for her poem which was published in science RHYMES in 2017.
Even if you don’t have the ice, you can find inspiration in Ice Flowers.
There is much more to be learned about Ice Flowers that are produced on stems of some species of plants. Please join the search for examples and share them with us.
Kurz, Don. 2004. Illinois Wildflowers . Cloudland.net Publishing
Lawler, D. M., 1988. A Bibliography of Needle Ice. Cold Regions Science and Technology, 15, pp. 295-310.
Related web pages showing products of Ice Segregation at the Earth's surface
Hair Ice - ice growing on pieces of dead tree branches on the ground or suspended
Needle Ice - ice growing up from the surface or near surface of soil
Pebble Ice - ice growing on small rocks through ice segregation
On the World of Ice in the Age of the Internet and Digital Cameras
Now that we have the Internet and digital cameras we can see things that years ago were known only to a few local persons. Please share your images and details of ice formations created through ice segregation. In the process we will gain a greater knowledge of these processes.
One of the many web pages of Dr. Jim Carter