In addition to the excellent translational analysis Hiroko Uno provides
I would like to suggest two additional reasons for Pound's choice of
A) rhythm--blue "works" with plum in a way that green does not. "Blue"
and "plum" are formed in the mouth and then forced out in much the same
way. They create a nice quick rhyme.
B) color Imagism- John Gould Fletcher, in fact, experimented with a
Imagistic poetry of color. (see the essay on John Gould Fletcher in
"Imagism and the Imagist by Glenn Hughes) Hiroko Uno's explanation
explicates the Image that Pound was trying to produce.
Portales, NM, USA