Flowers in literature often represent something that relates with femininity and womanhood.

On a deeper level, each flower typically represent things within themselves. Dandelions are symbolic of courage, geraniums are associated with folly, etc.

When used in literature, this can highlight the theme of a work.

In Steinbeck's "The Chrysanthemums," yellow chrysanthemums are correlated with lost love, abandonment, and optimism.