Question

Keel is characteristic of the flowers of
A. Glomar
B. Cassia
C. Calotropis
D. Bean

Answer 1

Hint: Papilionaceae is the family in which characteristic features of the keel flowers are present in it. Carina is a part obtained when the keel is the innermost fused into the petals. The lateral part of wings that obtained during the overlap by the lateral petals. And the wings obtained from the lateral petals again overlapped by petal and known as the name vexillum or standard.

Complete answer:
 In the inflorescence the arrangement of the flowers on a floral axis and continued growth depending upon the apex gets converted into the flower. Two types of growth of the flowers cymose and racemose. In the cymose inflorescence the main axis terminates into the flower and borne in the basipetal order such as jasmine. And in the racemose inflorescence the main axis continues growth in the flowers and borne laterally in an acropetal succession such as crotalaria.
In the pea or bean family fabaceae are irregular flowers that have 5 petals forming distinctive banners and structure that appear like a keel and wings. With the two lobes single petal structure known as a posterior patel and within the more petals structure known as lateral petals. Encloses of the essential organs fused into the remaining two anterior plates.

Therefore the correct option is (D).

Note: The shape of the keel flowers looks like a boat keel. The fusion of the bases of the keel due to the concave sides and characteristic features of keel flowers mostly found in the indigo era that present in the Papilionaceae family. And this type of arrangement is mostly found in the gram pea, indigo era and bean petals.