Kigo

Cherry blossoms (sakura), often simply called blossoms (hana) are a common spring kigo.

A kigo (季語, 'season word') is a word or phrase associated with a particular season, used in traditional forms of Japanese poetry. Kigo are used in the collaborative linked-verse forms renga and renku, as well as in haiku, to indicate the season referred to in the stanza. They are valuable in providing economy of expression.