316 SIGNOR U. MARTELLI ON 'THE CAUSE OF 
On the Cause of the Fall of the Corolla in Verbascum. By 
Signor U. Marretut. (Communicated by the President.) 
[Read 7th December, 1893.] 
Ir is generally known that if a plant of Verbascum (it is pre- 
sumably the same with every species) be struck smartly, the 
corollas already expanded will, after a minute or two, fall like a 
shower of leaves. This curious phenomenon, though well known, 
does not seem to have attracted the notice of the older botanists ; 
and I do not know of any old author who mentions this subject. 
Even so accurate an investigator as P. A. Micheli has made 
no mention of it, either in his published work or manuscripts *. 
Sir J. E. Smith seems to have been the first to write about it, 
in his ‘ English Flora’ (1824), vol. i. p. 311, where, after having 
described Verbascum pulverulentum, Vill., he says:—“If the 
stem of V. pulverulentum be smartly struck three or four times 
with a stick, all the flowers then open will, in a few minutes, 
throw off their corolla, the calyx closing round the germen, 
so that after eight or ten minutes none will remain on the 
plant.” Charles Darwin, in his classical work, ‘Forms of 
Flowers’ (p. 78), refers to the phenomenon in the following 
terms :—‘‘ It is known that many species of Verbascum, when the 
stem is jarred or struck by a stick, cast off their flowers. This 
occurs with V. Thapsus, as I have repeatedly observed. The 
corolla first separates from its attachment, and then the sepals 
spontaneously bend inwards so as to clasp the ovarium, pushing 
off the corolla by their movement in the course of two or three 
minutes. Nothing of this kind takes place with young, barely 
expanded flowers. With Verbascum Lychnitis and, as I believe, 
V. pheniceum, the corolla is not cast off, however often and 
severely the stem may be struck.” 
My observations do not precisely correspond with those of 
Mr. Darwin. I have cultivated, and sought out wild in the 
country, many plants of Verbascum Lychnitis, on which I have 
continuously made experiments, and have always noticed that if 
you strike the stem, the corollas fall off as in Verbascum Thapsus 
and many other species. I asked several friends to make this 
experiment at different seasons of the year, and their experience 
has confirmed my opinion. 
* These lie still unpublished in the Florentine Botanical Museum. 
