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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"


thapsus as the seed-bearer, and V. lychnitis as the pollen-bearer.
It is known that many species of Verbascum, when the stem is jarred or struck by
a stick, cast off their flowers. (2/25. This was first observed by Correa de
Serra: see Sir J.E. Smith's 'English Flora' 1824 volume 1 page 311; also 'Life
of Sir J.E. Smith' volume 2 page 210. I was guided to these references by the
Reverend W.A. Leighton, who observed this same phenomenon with V. virgatum.)
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.
phoeniceum the corolla is not cast off, however often and severely the stem may
be struck. In this curious property the above-described hybrids took after V.
thapsus; for I observed, to my surprise, that when I pulled off the flower-buds
round the flowers which I wished to mark with a thread, the slight jar
invariably caused the corollas to fall off.
These hybrids are interesting under several points of view. First, from the
number found in various parts of the same moderately-sized field.


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