Symbolism, Imagery, Allegory
If Anne grew up in the '60s, she'd be a total hippie. She's a flower child for sure, putting flowers in her hair and decorating her bedroom with them despite Marilla's disapproval.
And it probably comes as no surprise that chatterbox Anne talks about flowers a lot too—she likes to personify them, deciding that amethysts are "the souls of good violets" (13.23) and mayflowers are "the souls of the flowers that died last summer and this is their heaven" (20.2). The flower imagery continues as Anne grows up, and her friends place an iris in her hands when she pretends to be Elaine.
Because of the personality that Anne imagines into flowers, they often point readers to Anne's big imagination and her love of nature and beauty. Then there's their lifespan. Flowers bloom for a very short time—Anne often thinks about where their "souls" go after they wilt—so they can also be a reminder of something else that is short-lived: Anne's childhood.
Womp womp.