Describe a papilionaceous corolla.

Explanation

1. Petals 5, apopetalous, unequal and papilionaceous, vexillary or descendingly imbricate aestivation. All petals have a claw at the base.
2. The outer most petal is large called standard petal or vexillum. Lateral 2 petals are Ianceolate and curved. They are called wing petals or alae.

3. Anterior two petals are partly fused and are called keel petals or carina which encloses the stamens and pistil.
It is said to be butterfly shaped.