Floral ontogeny in Sophoreae(Leguminosae: Papilionoideae). III. Radial symmetry and random petal aestivation in Cadia Purpurea

Floral organogeny and development are described in Cadia purpurea, a legume with radial symmetry, unstable petal aestivation, and free organs, all unusual features among papilionoids. Flowers are usually solitary or, rarely, in few-flowered racemes. No bracteoles are formed. The order of organ initiation is unidirectional in each whorl, and the carpel initiates directly after petal initiation.The petal primordia remain small until all other floral organs have initiated, enlarged, and differentiated. Petal aestivation is variable, unlike the great majority of papilionoid flowers. Petal margins of Cadia grow straight outward rather than some petal margins curving inward inside the adjacent petal as is the case in other papilionoids. When adjacent growing petal margins of Cadia meet, chance determines which petal becomes positioned inside the other. Hence, the pattern of petal aestivation is random.