My World of Ice    

Dr. James R. Carter, Professor Emeritus

Geography-Geology Department

Illinois State University, Normal IL 61790-4400

Living in Midlothian, Virginia, USA


In 2003 I saw my first ice growing on plant stems. Since then, I have been introduced to ice in many different forms.  For the big overview with many photos and links to a diversity of pages. 

In 2013 I wrote an integrated series of 5 web pages examining the products of Ice Segregation in nature:  Ice Flowers on plant stems;  Needle Ice in the soil;  Pebble Ice on small rocks at the surface; Hair Ice on dead wood. These pages with many photos are kept up to date.

In fall 2013 The American Scientist published my article entitled "Flowers and Ribbons of Ice". A photo of one of my Ice Flowers graced the cover of the journal. The article was revised slightly, translated into French and reprinted as "Les fleurs et les rubans de glace" in Pour la Science.  Then it was revised slightly, translated into German and reprinted as "Blüten und Bänder aus Eis" in Spektrum der Wissenschaft.  In fall 2014 Investigacion y Ciencia reprinted the paper as "La belleza de las flores de hielo" in Spanish.

In 2020 I presented my story for Lunchbreak Science at the Science Museum of Virginia. It was recorded and put on YouTube under the title “Breathtaking Ice Formations: Discovering Frost Flowers, Needle Ice and Other Natural Ice Forms”

In 2021 “The Surface Expression of Ice Segregation: Needle Ice, Pebble Ice, Ice Flowers, and Hair Ice” was published in the Journal of Geography and Earth Sciences, Vol. 1, No. 9, pp 1-16. A copy of the paper can be downloaded from this site as a PDF

Ice Flowers are often called Frost Flowers. I found the name Frost Flower is also applied to an entirely different form of ice, leading to confusion.  I have tried to clarify the issue.

In 2009 I put together a web page with many links showing how much of these forms of ice relate to the diurnal (daily) cycle of warming and cooling. The page with many photos integrates most of my experiences up to that time but I have learned a lot since then.

Early in the process, I found a bibliography from Lawler, 1988, citing 267 writings going back to 1824.  I have tried to summarize some of the more relevant observations and studies from the past. 

Below is an update of my original web page with many links.  I am keeping this page because others may be comfortable with it and on occasion turn to it to find an item or a link.

I found my first ice in east Tennessee in December 2003 on Dittany, Cunila origanoides. 

In December 2004 I found Ice Flowers in east Tennessee on Verbesina virginica, White Crownbeard

In fall 2005 I found Ice Flowers on Verbesina virginica in northern Kentucky

Two weeks late I found a small ice flower on a Boneset-type plant I have yet to identify next to Needle Ice and a rod of ice I now identify as Pebble Ice. This find was about 30 miles west of Richmond, Virginia.

I was not able to find any Ice in 2006, but it was not for trying. I was looking. But I found seeds of Verbesinas and planted them in my yard.

In fall 2007 I had ice on plants on more than 20 days in my own yard.  

I had many different ice formations in fall 2008 and took many photos.

My web pages on Ice attracted emails of persons who found ice in many different configurations. So, I got some interesting inquiries. In January 2007 I explored extruding ice from pipes.  And, in winter 2007-08 I had even more success in extruding ice from pipes.  

Check out ice on branches of wood, more common in Europe than in N. America. I now know such ice on wood is called Hair Ice, but it was strange to me when I was sent my first photo in 2006.

In the Jan/Feb 2009 issue of Weatherwise I have an article entitled: Unusual Ice Formations: Studying the Natural Growths of Ice from Soils, Stems, Branches and Rocks, pp. 34-40. This article brought together for the first time the products of Ice Segregation at the Earth’s surface, being Ice Flowers, Needle Ice, Pebble Ice and Hair Ice.


My Story of How I Came to Understand Such Ice Formation

In fall 2004 I posted my web page for the world to see.  A few of persons saw my pages and sent me email.  I have corresponded with a number of these persons, and I have learned in the process. I called these ice ribbons and ice flowers based on their appearance but because the term ‘frost flowers’ is commonly used for another form of ice, I prefer ‘Ice Flowers’. Because these forms of ice may be whimsical in appearance, they may be given any name, including ice fringes, ice filaments, and rabbit ice.  

I employed bibliographic search tools to find out about frost flowers.  I found a few popular articles describing these unusual items but could find no authoritative papers explaining these ice formations.  I found two plant species associated with the name frost flower:  Dittany, or Wild Oregano, Cunila origanoides, and White Crownbeard, or Frostweed, Verbesina virginica.  Thus, I concluded this was a concern for botany.  I showed what I had found to many colleagues in the biological sciences and only one had personally seen these frost flowers and he thought they occurred on only Cunila origanoides.  He said he was sorry he never took this on as a research topic. 

Ice Flowers and Needle Ice

A person in Alabama sent photos, three showing ice flowers and one showing needle ice. He suggested they were related, but I rejected that association because I was convinced it was a botanical issue.  Then in Virginia in 2005 I found ice flowers and needle ice in the same immediate area, as shown above.  By golly, he was right. 

I went back to other correspondence and found another statement relating ice flowers and needle ice.  I then turned to bibliographic search tools and found there is a well-developed professional literature on needle ice.  In 1988 D. W. Lawler published “A Bibliography of Needle Ice” in Cold Regions Science and Technology (15: 295-310).  There are 267 items in his compilation going back to 1824.  I delved into many of the papers cited there. 

Stories from the 19th Century

Of particular note 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"  He goes on to make additional observations about the ice and the atmospheric conditions when these formed, all consistent with what I have observed more than a century and a half later.  He ends with "What share the physiological functions of the plant may have in the phaenomenon, or whether it be connected with the vitality of the stem at all, it is for botanists to decide." 

Herschel’s paper prompted Professor Rigaud of Oxford to recall his observation in 1821 of similar ice formations on a recently built stone wall.  “The portions of the ice (with a single exception) were formed at the edges of the stones -- indifferently at the tops, to bottoms, or the sides, but the curvature was uniformly turned inward from the mortar itself, in which case the threads of ice were formed in a horizontal line, and I think (for of this I made no memorandum) parallel to the layer of the mortar.”  Philosophical Magazine, Feb. 2, 1833, 190-191.

In the same journal (The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science, Third Series) of May 1850, 329-342, John LeConte, M.D., of the University of Georgia wrote about many instances of observing frost flowers and needle ice in Georgia.  He quotes liberally from Hershel (1833), for he appreciated the words as I do.  LeConte also produced some lovely descriptions such as ". . . the traveler who passes along the level roads of this region soon after sunrise cannot fail to be struck with the remarkable accumulations of voluminous friable masses of semi-pellucid ice around the footstalks of the Pluchea which grow along the road-side ditches.  At a distance they present an appearance resembling locks of cotton-wool, varying from four to five inches in diameter, placed around the roots of plants; and when numerous the effect is striking and beautiful." p. 330.  He observes that in some cases ice had formed on the same plant on consecutive nights "when the wood was not rifted." p. 332.  He also makes observations about what we now call needle ice and argues "that both of the phaenomena must be referred to the same cause.  If we admit an identity of cause in the two cases, it is obvious that it must be purely physical . . ." p. 336.

In 1880, the Duke of Argyll writing in the January 22 issue of Nature described such ice formations and asked for a scientific explanation of this phenomenon.  In the January 29 issue three persons weighed in with opinions based on what they had seen.  In the February 19 issue the Duke of Argyll responded.  In the February 26 issue one of the earlier writers and a new writer offer their suggestions based on ice formations they have seen. All of these contributors were from what we now call Great Britain.  In the April 22 issue Wm. LeRoy Broun from Vanderbilt University describes the growth of needle ice and compares it to the ice formations observed in Europe.  Broun does not reference LeConte who was also from the southeastern U.S.

A report on the meeting of the Physical Society in Berlin, in the March 13, 1884, issue of Nature includes a discussion from Prof. Schwalbe on flowers growing from rotten twigs lying on the ground as ". . . ice-excrescences of soft, brilliant, asbestine appearance, and uncommonly delicate to the touch. . . ."  Prof. Schwalbe brought some of these withered and rotten twigs with him to Berlin, and it was in his power to produce on them at any time the phenomenon just described.  For this purpose all that was needed was thoroughly to moisten the twig, in such a manner, however, that no water dropped off, and then to let it cool slowly in a cold preparation.  Ice-excrescences also appeared of themselves on twigs lying in the garden whenever the temperature fell below 0 degree C. in the night." (p. 472) He made reference to the explanations of LeConte, 1850.  I originally assumed these were ice flowers but subsequently I foud others reporting these phenomena on rotten twigs.  I have a separate web page on these ice formations, which are called Hair Ice, Haareis, Kammeis, Pipkrakes and Silk Frost. 

In later editions of Nature, there were a series of letters reporting on ice formations and reacting to earlier letters.  Most of these reports relate to what was obviously needle ice but, in the January 1, 1885, issue B. Woodd Smith tells of a friend who “. . . picked up a piece of a dead beech-branch which was covered with filamentous ice, such as is described by the Duke of Argyll and others.”  This person found the ice reappeared again the next morning when it was left out overnight.  (p. 194). 

I marvel at the observations and vocabulary of these authors, writing more than 120 years ago. Do we know more about frost flowers and needle ice than they did back then?  We certainly know more about needle ice, as evidenced by the many articles cited in Lawler's bibliography.  Among these papers are reports of scientists growing needle ice and controlling the rate of growth. 

Lester F. Ward, “Frost freaks of the dittany,” The Botanical Gazette, 1893, observed these near Accotink, Virginia, USA.  He has stylized drawings of the stems and ice ribbons.  He writes that the article belongs in a botanical journal because of all of the plants in the area the ice formations occurred only on Cunila Mariana, dittany.  He and a colleague tasted the ice and inferred from this that the water was not “. . . distinguishable from pure distilled water . . .” p. 185 Ward said he was able to find no records of others observing this phenomenon.  He also wrote: “It is possible that this is the first time that Cunila Mariana has been discovered to be a frost-weed.  At the time the discovery was made it had quite escaped my memory that Helianthemum Canadense behaves in a similar way.” P. 185. 

Ward references Gray’s Manual, 1848, as describing such ice formations on Helianthemum Canadense, or frostweed.  As similar statement appears in the Eighth Edition of Gray’s Manual of Botany, 1970, on p. 1017 and notes that Helianthemum Bicknellii is also called frostweed. 

Ward also refers to the book Sharp Eyes by Wm. Hamilton Gibson, dated 1892.  I got to see the 1904 edition of this delightfully illustrated work, where Gibson writes about what can be seen in nature every week during the year.  The November 3d entry is ‘The Frost-Flower as it appears on Helianthemum Canadense’.  He notes it has three distinct types of blossoms during the year.  In November “the flower from which the plant is named, but which few people ever see.  Almost any morning during the past week, after a severe frost, would have shown it to us among the stubble where the plants are known to grow, glistening like specks of white quartz down among the blown herbage close to the base of the stem.  It is a flower of ice crystal of purest white which shoots from the stem, bursting the bark asunder, and fashioned into all sorts of whimsical feathery curls and flanges and ridges.  It is often quite small, but sometimes attains three inches in height and an inch or more in width.  It is said to be a crystallization of the sap of the plant, but the size of the crystal is often out of all proportion to the possible amount of sap within the stem and suggests the possibility that the stem may draw extra moisture from the soil for this special occasion.  The frost-flower is well named.”  The sketch accompanying this text shows a blossom of ice in one image overlaid on top of the plant in full bloom in summer. 

And in the Early 20th Century

Prof. Cleveland Abbe, “Ice Columns in Gravelly Soil,” Monthly Weather Review, 1905, 157-8, writes about needle ice and references LeConte, 1850.  He notes that “Only once have I seen the corresponding phenomenon of a thin ice sheet of parallel ice columns exuding from a vertical crevice in the bark of a tree, many beautiful examples of which are given by Professor LeConte and Sir John Herschel.”  Abbe rejects the explanation of LeConte and offers his own suppositions.  He calls for someone to repeat the process in the physical laboratory.  There is a concluding remark “This explanation of the growth of hollow columns of ice in gravelly soil applies with slight changes to the hollow stems and plates of snow crystals.  The whole subject of the growth of crystalline forms needs elucidation.” p. 158. 

Then I found Coblentz, “The Exudation of Ice from Stems of Plants” in the Journal of the Franklin Institute, 589-621, Nov 1914.  Coblentz was a physicist working for the National Bureau of Standards in Washington, DC.  In 1913 he found some frost flowers in Rock Creek Park and started observing what he saw.  He systematically made observations, took notes and carried out many experiments with the help of colleagues.  He found that in the mix of plants in the rocky slopes, the ice flowers occurred only on Cunila mariana, or Dittany.  He cut off stems and inserted them in moist soil, test tubes and crucibles.  He reported on how rapidly water moved up the dry stems of Dittany and was able to grow ice ribbons, what he also called ice fringes and ice filaments.  He showed that the roots of the plant are not necessary for the formation of ice, nor is the outer bark. He applied different treatments to the stems and showed that the water for the ice comes from within the stem and is not deposited from the air. He noted one ice flower weighed 5 grams and observed that many were of this size. 

Other than Schwalbe (1884) in the Harz Mountains, Coblentz appears to be the only person who has systematically grown ice ribbons and reported on them.  (Mention should be made of Bruce Means, The American Gardener, Jan/Feb 2005, 36, who mentioned he grew beautiful ice flowers on stems of flat-seed sunflowers.) Coblentz has many photos of the ribbons he grew, but the copy of his paper I saw was on microfilm and the photos were not very clear.  He has sketches of the setup of his experiments and of some of the ice ribbons he grew and thus Coblentz demonstrates the ice ribbons are a product of a physical process.  This is an important paper to understand the nature of these ice formations because today many web sites attribute the ice to frozen sap.

The Environments in Which Such Ice Formations Are Found

But the process works only on the stems of particular plants.  Coblentz carried out his observations on Dittany, Cunila mariana, which is now known as Cunila origanoides.  Many persons have observed that Frostweed (Verbesina virginica) or White Crownbeard, produces such ice ribbons.  And others write about Frostweed (Helianthemum canadense) and note it produces these ice formations.  I have seen many examples of ice formations on Dittany and White Crownbeard, but I have not been able to find any photographic images of such ice on frostweed Helianthemum canadense.  But I will continue to look.  Subsequently, I have found such ice formations on other plants , as noted elsewhere. 

LeConte (1850) wrote “The plants on which I have observed it are two species of the genus Pluchea of DeCandolle, or Conyza of the older botanists, viz. Pluchea bifrons and P. camphorate.”  I have not been able to relate these species names to ice formations nor have I been able to find new species names that were formerly known by these names.  I assume LeConte observed his ice formations on one of the three species we know about today.

Herschel (1833) stated that he first saw such ice “. . . round the roots and stumps of some dry and decaying thistles.”  The second time he found such ice on stumps of a bed of heliotropes, but these stumps included stems as he describes in his paper.  I cannot tell what specific plants were involved in the formation of these ice formations. 

A. Hillefors wrote about “Needle Ice on Dead and Rotten Branches” in Weather, 1976 (31, pp. 163-168).  He observed these in Sweden.  The photos I saw were on a poor-quality photocopy.  Then, in early 2006 I received an email and three photos from Wales showing flowers of ice growing from rotten branches.  In these photos the ice appears to be a little more needle, like but it is quite attractive.  Subsequently, I have received photos of such ice on pieces of rotten wood on the ground from a number of places in Europe and from the Pacific northwest and eastern Canada.  These ice formations are not the same as Ice Flowers on stems extending up from the ground.  But they occur under similar weather conditions.  These have been called Haareis, Kammeis, Pipkrakes and Silk Frost.  I am certain these are the same ice formations Schwalbe wrote about in 1884. We now know this is Hair Ice.

Interestingly, while the ice formations based on dead and rotting wood are mostly from Europe and the Pacific NW of America and the ice flowers based on the stems of plants are mostly in the eastern part of the USA, there is a photo of a classic ice ribbon on a stem on the cover of the Journal of Glaciology (1993, 39:132).  This photo was taken in northern India at 16,000 feet.  Then in 2008 I received a link to another photo of an ice ribbon in northern India.  So, I must be careful when making generalizations about what occurs where in our big world.

In December 2006 I received an email from The Weather Doctor Kieth Heidorn who referenced his web page where he has two photos of long and thin ice ribbons that formed on a metal fence rail.  The photos came from Sheryl Terris of Vancouver Island, Canada.  She is quoted as saying she gets these ice formations year after year on the same gate. These appear to be consistent with the observations of 1821 of similar ice formations on a recently built stone wall.  With her permission I put together a web page showing her great photos.  Then I experimented and was able to extrude ice that is very similar to Sheryl's photos.

In summary, we know the formation of frost flowers, ice flowers or ice ribbons is a physical process, not related to the growth of a biological organism.  These ice formations occur on the stems of a few species of plants and on certain pieces of rotten wood on the ground.  I thought I could count the numbers of species on which these form and then I hear from a woman in central Tennessee who found these on New York Ironweed Veronia noveboracensis.  She convinced me she knew her plants and thus I added the stems of another plant on which these occur.  And, through these web pages I have heard from others and now have identified about 40 plants on which these occur.  I thought they occurred only on dead stems, but last fall I saw them form on stems that were alive.  

There are probably more.

These form when the water in the soil remains above freezing while the air temperature falls below freezing.  The conditions would be optimal on clear nights with no wind, when the dominant cooling process is net radiation.  This fits the description of many reports of observations of ice ribbons, but there are reports that these also occur under quite windy conditions.  See Tim Ernst:  for the dates of 11/24/03 and 11/25/03. 

The Tim Ernst story has evolved. See the link to his archives at:  

It appears that the images I referenced in the first decade of the 20th Century are not currently available as of 2020. After observing these many times during the fall and winter of 2007 I know the only criteria is air temperatures below freezing and a soil temperature above freezing. 

On the Processes of the Formation of Ice Flowers, Frost Flowers and Ice Ribbons

What is the process that leads to the formation of these ribbons of ice?  The stems of these plants and certain rotten pieces of wood serve as conduits to transmit water from the soil which is above freezing to a surface which is below freezing.  (I cannot conceive how a fence rail could stay above freezing while the air outside is well below freezing.  I'm thinking about that.)

Charles Knight of UCAR offered an explanation in an email (2 Feb 05): “The reason this sort of thing happens is that ice cannot grow in supercooled water through very small openings, but water, of course, can flow through the openings.  So, one can have an ice crystal in contact with a wet porous material, and it grows at the contact, pushing the ice crystal away while the supercooled water flows to the contact.” 

There is another necessary condition for the formation of the ice -- the dew point temperature of the air must be below freezing, and the temperature must fall to the dew point, or more properly the frost point.  When the temperature falls to the frost point, ice will start to form on surfaces.  The crystallization of the ice should be sufficient to start the growth of ice flowers or Haareis, etc.

Knight pointed me to the paper by Ozawa and Kinosite, “Segregated Ice Growth on a Microporous Filter” Journal of Colloid and Interface Science, (132: 1, 1989).  They define ice segregation as “. . . the phenomenon in which, through freezing, ice grows out from moisture-containing porous material such as soil.” (p. 113).  They conducted experiments growing ice over many hours while making very detailed measurements.  They found the water to be supercooled and colder than the surface where the ice forms. But, in their experiments they started the freezing process by introducing a droplet of ice on the surface of the porous filter.  They show that the latent heat of fusion flows from the surface of freezing to the supercooled water.  They conclude their paper by considering these processes in soils and the formation of needle ice and/or ice wedges.  They do not seem to be aware of ice ribbons or frost flowers.

So, what we observe when we see ice flowers or frost flowers is ice segregation along the stem of a plant.  When the supercooled water penetrating through the stem encounters the first crystals of frost the supercooled water turns to ice. That process continues and new ice is added at the stem-ice boundary.  This pushes the old ice out and away from the stem.  If the stem is not ruptured over the night, the process can go on continuously until the ambient air temperature rises above freezing or there is a limit to the supply of water in the plant stem and soil.

I have observed that such ice flowers will reoccur on subsequent nights showing that the water in the stems does not always freeze.  And it is known that such ice formations may occur in the same area over many nights in late fall and winter. 

In fall 2007 I observed the rates at which such ice forms on stems of White crownbeard in my own yard.  I show this by a sequence of three photos over one night.  Forrest Mims III has a better record with a time-lapse video on his YouTube site. 

Thanks to the wide reach of the Internet, we are learning more day by day.  If you have observed the growth of these ice flowers, ribbons or whatever you call them and can add insight into the process, please let me know.