Cassia flowers exhibit imbricate aestivation, where the petals overlap in a particular way. The flowers are zygomorphic, meaning they are bilaterally symmetrical. Additionally, the inflorescence in Cassia is a corymb, which means that the flower stalks are arranged in a flat or slightly convex shape, with the outer flowers blooming first.
Thus, the correct statement is "Imbricate aestivation, zygomorphic, corymb."