Understanding the development and evolution of novel floral form in Aquilegia.

Highlights: [•] Aquilegia exhibits several floral innovations, including petal spurs and a fifth organ type, the staminodium. [•] Petal identity is established by a subfunctionalized APETALA3 paralog. [•] Development of the nectar spur depends on anisotropic cell expansion. [•] Staminodium identity appears to depend on the evolution of one staminodium-specific paralog. [•] Applying our genomic resources to interfertile Aquilegia species will elucidate these features as well as many others. [ABSTRACT FROM AUTHOR]