corolla

/kəˈɹəʊlə/

IPA: /K ER0 AA1 L AH0/

noun
  1. 1

    An outermost-but-one whorl of a flower, composed of petals, when it is not the same in appearance as the outermost whorl (the calyx); it usually comprises the petal, which may be fused.

Source: https://en.wiktionary.org/wiki/corolla