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Frostweed (Verbesina virginica) Crystallofolia, Winter 2009–2010

by Bob Harms ()
VEVI3 at pool edge 5Dec09
At water's edge, 5 December 2009
Fall 2009 was exceptional in two respects. The record drought of 2008–2009 ended suddenly in mid September, followed by heavy rains well into December. Then early December was exceptionally cold, with a hard 19° frost on Dec. 5 accompanied by heavy condensation frost on all vegetative surfaces (not to be confused with crystallofolia).

I had wondered why V. virginica in wet creek areas didn't exhibit crystallofolia in 2007, and suspected that the wet soil had managed to counteract the freezing air temperatures. In 2009, for the first time, I found frost formations at water's edge, as shown above. More speculation:

The late season moisture also caused blooming to occur very late. On Dec. 5 plants were still in bloom, stems had not yet hardened, and contained a lot of water. The frost formations were significantly larger than before and occurred almost along the entire stem. [Click images to enlarge.]
VEVI3 frost formation along stem
Dec. 5: Note the green leaves and frost formations high up the stem.
VEVI3 group, Dec. 20
Dec. 20: Same area as above, leaves dry
VEVI3 group, Dec. 27
Dec. 27: Same area

A large plant in bloom, 5 December 2009

Stem detail
And although the formations were larger than before, owing to the internal moisture, the condensation frost was also very strong and seemed to interact with the crystallofolia – restricting the fine detail of the ribbons.

Base of large plant, 5 December
large plant, now dry, 20 Dec
Same plant as above, 20 December 2009
stem base detail, 20 Dec
Stem base detail, 20 December 2009

Additional images for winter 2009–2010; click to enlarge.

5 December 2009
narrow stem formation detail of narrow stem large plant base detail
20 December 2009
large plant base detail of narrow stem complex frost detail
27 December 2009
same large plant Jan 1 ice detail Jan 1
1 January 2010
angelwings 8 Jan 10 frost group 8 Jan 10 long ribbons 9 Jan 10
8–9 January 2010, 17° F
same large plant Jan 10 frostwings Jan 10
10 January 2010, 13° F