Terry Delaney has given a reference to the derivation of "apoptosis"
(to do with falling of leaves of petals) and Tobias Baskin has
pointed out that botanists instead use "abscission" to describe the
falling of plant parts. F.T.Addicott, in his great botanical book entitled
"Abscission" * does not use or refer to "apoptosis" anywhere, but
does define and use "cladoptosis", the falling of branches. He also
points out that "abscission" is really an inappropriate word to
describe the phenomenon, because its derivation implies that the
parts are artificially severed - as by applying "scissors" - rather
than as the outcome of an internal, natural process.
*Univ. of California Press, 1982