In a Station of the Metro
Pound neatly divides the two lines between tenor (the subway scene) and vehicle (the image of petals on a branch). The vehicle paints a vivid picture while the “apparition” of faces in the tenor remains shadowy.
The apparition of these faces in the crowd;
The slant rhyme of “crowd” and “bough” makes the poem a subtle couplet.
Petals on a wet, black bough.
(“In a Station of the Metro” first appeared in Poetry magazine in April 1913.)