104 MISSOURI BOTANICAL GARDEN BULLETIN 
FROST FLOWERS 
So-called ‘‘frost flowers’’ are such striking and beautiful 
objects that to one who observes them for the first time they 
are regarded as being something rare and perhaps not even 
previously known. But just a hundred years ago Stephen 
Elliot in ‘‘A Sketch of the Botany of South Carolina and 
Georgia’’ wrote of the marsh fleabane: 
“This plant exhibits frequently a remarkable phenomenon. 
In every cold frosty morning during the winter, crystal- 
line fibers nearly an inch in length shoot out in every 
direction from the base of the stem. It would appear as if 
the remnant of the sap or water, absorbed by the de 
cayed stem, had congealed, and had burst in this manner 
through the pores of the bark. Does this proceed from any 
essential quality of the plant, or from its structure?” 
Since Elliot’s time many scientists have made similar ob- 
servations and concerned themselves in attempting to explain 
the cause. Sir John Hershell, in 1883, recorded the faet that 
the stalks of thistle and heliotrope produced formations of 
ice crystals, and up to the present time at least thirty differ- 
ent plants have been recorded as forming frost flowers, in- 
eluding not only herbaceous annuals and perennials, but 
trees, such as walnut, pawpaw, Paulownia, ete. These 
crystals sometimes take the form of single columns on the sur- 
face of cut portions of the plant, or they burst through the 
bark, producing all sorts of fluted flanges and ridges. The 
accompanying plates, from photographs taken in the Garden, 
show shell-like structures of ice of pearly whiteness, curled 
in every variety of form, not unlike the petals of a flower. 
‘While ice crystals are by no means confined to a single 
species, as has sometimes been supposed, there are only a 
comparatively few plants in which this phenomenon ean take 
place. The roots must retain their vitality long after the 
stems have died, and continue to force up water which either 
freezes on a cut or wound or finds some other outlet: through 
% the bark. The tendency of stems to contract in eold weather, 
squeezing out any surplus of water present, may likewise be 
a factor in the formation of ice crystals, although this is 
not the ease in those illustrated in the accompanying plates. 
