Question

Vexillary aestivation is characteristic of the family
A. Fabaceae
B. Asteraceae
C. Solanaceae
D. Brassecaceae

Answer 1

In vexillary aestivation there are five petals in total. Among them two are the lateral petals called wings that overlap the two small anterior petals known as keel, which overlap further the largest petal called as standard petal. These are the general characteristic features of the vexillary aestivation.

Complete answer:
Aestivation is defined as an arrangement mainly in flowering plants where in the flower, the accessory organs in the flower are in relationship with one or the other floral bud i.e., the starting of a flower, most often in line the sepals and petals are organised. In vexillary type, the posterior part of the petal of flower overlaps with the two lateral parts of the petals, the latter then overlaps the two first anterior petals.
One feature of the fabaceae family is the presence of descending or vexillary aestivation. In this type two petals that are lateral shaped, called as wings of lateral petals, which further overlaps the anterior petals called as keels.
It is also known as corolla of papilionacea. Generally aestivation is referred to as a perfoliation; it is also known as vernation i.e. the arrangement style of leaves within a vegetative bud.
The flowers that come under the Fabaceae family are characteristic and zygomorphic. The perianth of the flower generally has a calyx and corolla, consisting five segments each. In fabaceae family the petals show overlapping (called as imbricate) within bud plus the presence of posterior petal (i.e. the banner or flag) outermost (called as exterior) in the same position. One more characteristic feature is the presence of the two lowermost petals that are joined together known as the keel petals. The lateral petals are generally referred to as the wings.
This type of arrangement of floral whorls in fabaceae family flowers is known as vexillary aestivation.

Hence, the correct answer is option (A).

Note: The Corolla type vexillary aestivation is a characteristic of the family Papilionaceae in which there is a presence of petals. In this, boat shaped petals are known as keels, two lateral, one posterior petal is known as vexillum is largest in Papilionaceous corolla and curved types petals are known as wings.