Quoting myself (slightly edited) from an old thread asking the same question:

Not a flower, but the strawberry tree is the Italian national plant, because its colours (green leaves, white flowers and red berries) recall the Italian flag. This was pointed out by Giovanni Pascoli in a poem (Al corbezzolo, "To the strawberry tree"), where he cites a passage from the Aeneid by Virgil, where this plant is mentioned.

Speaking of flowers, the lily is famously the symbol of Florence, whose coat of arms bears the* giglio bottonato* (literally "buttoned lily").