Keel is characteristic of the flowers of

Step-by-step solution

The bean or legume family is one of the most common plant families. Flowers in bean family typically have their two bottom petals grown together along one side forming a structure a bit like a narrow but deep scoop. This special Bean-family kind of two-in-one petal is called the keel, like the keel of a boat. Bean blossoms with this configuration are said to be papilionaceous.