hi
i've read about ur question and one Chinese book says that Colchicum is
a kind of alkaloid, which is a kind of secondary metabolite that plants
produce..the alkaloid is hold in the laticiferous tube (a kind of
internal secretory structure) so this may be why it has no direct
effect on plant cells but are used to protect themselves, attract
insects(esp.entomoplily plants) or sth. like that..
its difficult for me to use english so i may not discribe it
accurately...u'd better look for some more info..