a, keel petal; b, side petals; c, banner petal.
This image is from Red Bud in the Drugs and Medicines of North America.
Henriette's herbal is one of the oldest and largest herbal medicine sites on the net. It's been online since 1995, and is run by Henriette Kress, a herbalist in Helsinki, Finland.
http://www.henriettes-herb.com - Copyright 1995–2022 Henriette Kress.