Monday, November 30, 2015

Frost Flowers

"Frost flower" in full bloom - Tonya Smith
By Tonya Smith* 
I know frost flowers have been around for a long time, but I'm only three years new to the discovery of them.  I have walked the same trail year round since 2003 and it wasn't until 2013 that I happened upon the frost flower gardens one morning after a hard freeze at the end of October.   Now I watch the weather closely in late Fall, so I can be sure not to miss a walk among nature's most delicate white flowers which disappear quickly with the rising sun's warmth. Nature giveth and nature taketh away. Probably a good thing as I had more than enough sticky seeds and burrs to pick off my clothing from laying on the ground to get the pictures.  Frost flowers are just one of the many things I am thankful for.
Tonya Smith
Their scientific name is Crystallofolia which was coined by Botanist Bob Harms from the University of Texas.  This is from Latin crystallus, ice, [itself from Greek κρυσταλλος; cf. κρυος 'frost']and folium leaf. These elegant formations have been given many names, metaphorical in nature, most commonly ‘frost flowers’ (or ribbons), a formation which is neither frost nor a flower. These common names, however, are easily confused with terms describing true frost from condensation on a cold surface as well as any picturesque ice formation.

These frost metaphors are of fairly recent origin, not current with 19th Century treatments of the subject (e.g., 'frost freak' was used by several scholars).  I thus propose folium, leaf, as a more appropriate metaphor, since like leaves these formations emerge laterally from the stem, and the enormous diversity of forms finds better matches with leaves than with flowers and ribbons — although this is perhaps less poetic. Perhaps more significantly, the physical process by which water moves to the ice formations is analogous to the transpiration that brings water from the roots to the leaves. My perspective is not new: German botanists in the 19th Century used the term 'Eisblatt' ('ice leaf')."

Frost flowers, also referred to as ice flowers, only appear on the stems of a limited number of species. The two most common in Missouri are Dittany and White Crownbeard**. Stinkweed (Pluchea camphorate) is a third but this plant is not widespread in Missouri.
Dittany - MDC Discover Nature field guide
Dittany (Cunila origanoides)

Sometimes called "wild oregano," dittany (like true oregano) is a member of the mint family and can be used as a culinary herb and in teas. Look for it on dry, wooded slopes in Ozark counties. http://mdc.mo.gov/discover-nature/common-plants-and-animals/wildflowers-and-grasses/frost-flowers
White Crownbeard- MDC Discover Nature field guide
Crownbeard (Verbesina virginica)
It’s called “white crownbeard” for the look of the flowers. “Wingstem” describes the narrow green “wings” running along the stem, especially on the lower half of the plant. It’s called “frostweed” for the strange and beautiful formations formed at the stem bases after a sudden hard frost.  Bob Harms with the University of Texas points out that the stem itself doesn't split. The epidermis ruptures along with the cortex and other tissues that seem tightly bonded to it.


There may be more opportunities for frost flowers as the temps have warmed back up and rain is returning adding more moisture, but it is not likely they will be as large or as numerous. If you missed them this year, keep watch for areas where the common White Crownbeard grows so you can visit this spot in the early morning of next year's first hard freeze.

* Photographs and text by Tonya Smith who is a member of our latest Master Naturalist class.
**   Some sources list yellow crownbeard as an occasional source of frost flowers but we have never found any on our plants over the years.

Editors note:

Late ice ribbon on Dittany - REK
Don't give up on late season frost flowers.  We found them on 40 mornings a few winters ago.  Late season "flowers" tend to occur low on the stem an produce more narrow ribbons like this picture.  They continue until a prolonged freeze kills the plant tissue down in the soil.   As perennials they will return next year.
Check out these resources for further information on frost flowers as well as the resources page:
Dr. James Carter references:
Frost Flowers
Ice or Frost Flowers?- James Carter
JR Carter at Illinois State/ice/diurnal/
Dr.Robert Harms

biosci.utexas.edu/crystallofolia.html
scientificamerican.com/cocktail-party-physics
Other sources of frost flowers

1 comment:

  1. Beautiful captures and this is the first of my knowledge of such thing as Ice Flowers and now will keep eyes low and peeled for them as I venture with my camera, thank you so much for this beautiful info. =0)

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