Ice Flowers on Penta - a new perspective  

Dr. James R. Carter, Professor Emeritus

Geography-Geology Department

Illinois State University, Normal IL 61790-4400

 

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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.  Most Americans who have seen Ice Flowers are likely to have seen them on the wild flower Verbesina virginica , commonly known as White Crownbeard and Frostweed.  Ice Flowers are known to occur on other plants and occasionally reports are made of other observations.  

I planted Verbesina virginica in my yard which is where I have seen most of my ice flowers.  Last year I observed a small formation of ice at the base of a flowering plant in a pot on my deck.  The plant was Penta, a commercially sold ornamental.  

Figure 1 - On the left is a close up of the plant in the pot in late November 2013 showing the ice at the base of the stem.  At this time some of the bark and leaves of the plant are still present.  On the right is the same plant two weeks later after a thaw and new ice had formed.  In this photo the bark and leaves have been stripped off the stem and the ice is smaller.

I found it interesting that this ornamental had some ice, and I liked the flowers.  So, in spring 2014 I bought five plants from my local nursery and placed them in two places in my yard.  The two pink ones grew to about 18 inches (45 cm) tall.  The three red ones were not as tall or full, probably because they were in a drier site.  They grew to a height of about 13 inches (33 cm).

Figure 2 - Cluster of two pink Pentas about 18 in (45 cm) tall on left and the group of three, shorter red Pentas on the right.

In early November 2014 I had the first formation of ice on plants in the yard.  To my surprise the Pentas had very good ice.  Actually, I should not have been surprised because in my correspondence I have some photos of ice on Pentas sent to me by Jan MacDougal of Charleston, South Carolina.  The ice I had is consistent with that in her photos.

It is hard to compare the Penta ice to that on the Verbesina virginica stems because the Verbesina stems are straight and unbranched while the Pentas have many branches starting at the base of the plant.  It is my impression that the ice on the Pentas was more full, and extended over a greater proportion of the total length of stem, than on any of my Verbesina stems.     

Figure 3 - Ice on the two stems of pink Pentas in the front yard.  This was November 12 and before this date I had cut off the leaves of the plant on the right so I could see the ice.  The plant on the left still has its leaves and it is hard to see the ice.  In the case of the plant on the right, note how ice is formed on all of the branches of stems.  

The ice on the three stems of the red Pentas was not as easy to observe because the plants were smaller, in a mix of other plants and the leaves were dense.  In the left photo below one can see lengths of white ice extending off in many directions, all on the same plant.  

Figure 4 - On the left ice forms bright white rods along a number of stems that extend up and to the right from the base behind the tag.  Here we see how the ice has peeled back the bark off the stems.  After the ice melts the bark falls off or is easy to remove.  Note the tag identifies this as the Butterfly Deep Rose variety of Penta.  I call it red.  On the right is ice on two cutoff branches of the neighboring Penta.  These are about 2 inches (5 cm) long.  On these I removed the bark when I cut the stems exposing the woody stalks.  Obviously, the ice forms on the woody part of the stem and not on the bark.     

Refrigerator experiments with Penta stems

Years ago, I found a way to grow ice on small pebbles in a refrigerator with some success.  A couple of times I had tried to grow ice on dead plant stems with no success.  Then this fall I inserted green stems of Verbesina virginica in my refrigerator setup and to my surprise grew ice flowers.  When I found ice on the stems of Penta in my yard, I cut some stems and put them into my refrigerator setup.  More success.

Figure 5 - The ice chest above serves to provide an environment where I can grow ice at any time in a refrigerator.  The ice chest and peach colored foam provide insulation from the cold of the freezer.  The small plastic container in the center is filled with wet sand and plant stems are pushed down into the sand.  Below this plastic container is a light bulb which provides the heat source to keep the water in the container liquid. When adjusted properly the temperature of the air above the sand is below freezing but the water in the sand remains liquid.  On the right I am holding a small stem of Penta that was in the sand.  The ice grew on that portion of the stem above the sand through the process of ice segregation.  Normally, I let this setup run for about 24 hours.  

I check my refrigerator setup every day or every other day.  I have not been in a position to see how many hours are required to get good ice.  The temperature of the air in the freezer varies around 14 F (-10 C).  As discussed on my Pebble Ice page , the temperature in the freezer varies as the freezer cycles on and off.  That cycling sometimes produces waves or ridges in the ice. 

I am now conducting many experiments with different plant stems. By the time I discovered I could get good ice in the refrigerator with green plant stems the growing season was near the end.  I am looking forward to next year to try a variety of stems at various stages of growth. 

Figure 6 - In this setup I have one piece of Verbesina virginica in the center and pieces of Penta stems at the four corners.  The Verbesina stem is much larger in diameter and not surprisingly the ice flower is larger.  But the ice flowers on the Penta stems are distinct and voluminous.  The example in the upper left is quite large on a stem that has become fractured.      

Based on this limited opportunity to see the products of ice segregation on the stems of five Penta plants in the past month, I am extremely pleased.  I will be growing Pentas again next year and will be more prepared for the presence of ice as cold weather moves in.  And I want to harvest green stems over the summer to put in my freezer to see if and when they support the growth of ice flowers.  

When people ask where they can find plants which produce ice flowers, I wish them luck.  I brought seeds into my yard for Verbesina virginica and that is where I have found my ice flowers.  I have tried to find other plants and have had marginal success.  Now I can tell everyone to purchas Pentas to enjoy the flowers in the summer and observe the ice flowers in late fall.  I know there are other plants that produce such ice but we have not examined them thoroughly. 

Why do a few plants produce ice flowers and most do not?  

I have been looking for an explanation to this question by looking at my stems of Verbesina virginica.  I have access to four types of Verbesina and only one of them produces ice flowers.  The stems of these four types of Verbesina are very similar so why does one produce ice flowers and the other three do not?   Now, I find the Penta stems produce ice flowers and those stems are distinctly different from all of the Verbesina stems. 

And, in the last month I have found some small plants in my yard that appear to produce ice flowers.  I want to do more work with those stems before I say anything more.  I am looking for green stems of many plants next summer to test in my refrigerator setup. 

This page is an addendum to my larger page on Ice Flowers . 

When the process of ice segregation occurs on some pieces of dead wood 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 .  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 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. 

For other perspectives on ice see my web pages at http://www.jrcarter.net/ice/   Feel free to contact me at  jrcarter@ilstu.edu   to share your photos of ice of this nature.

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