Question

Zygomorphic flower with vexillary aestivation, diadelphous androecium and marginal placentation occurs in
A) Pisum
B) Aloe
C) Brinjal
D) Belladonna
E) Asparagus

Answer 1

Hint: The arrangement of stamen and petals are different in different types of flowering plants. In some flowers stamens are attached to the anther, in some conditions stamens are fused together, and in some conditions stamens are attached to the perianth accordingly the flowers are classified.

Complete Answer:
- The flower part consists of sepals, the green leaf-like part of the flower. It involves the protection of flowers when it is in bud form. Petals are the coloured part of the flower that attracts the pollinators towards itself.
- Stamen is found inside the petals made of filaments and anther. The anther produces pollen grains that carry the male gametes, therefore the stamens is the male reproductive part. Carpel is found in the centre of the plant that is in flask shape. It is divided into stigma, style, and ovary.
- The pollen grains from the stigma fall on the carpel, and from the style tube it reaches to the ovary for fertilization of the egg for reproduction. In other words we can say that the flowers consist of four whorls; calyx, corolla that is composed of petals, androecium that contain the stamen, and the gynoecium that consists of one or more carpels.
- Depending on the arrangement of these four whorls the flowers are classified further. The epipetalous are the flowers in which androecium is attached with the flower petals, therefore, epipetalous is the conditions of stamens.
- For example, Datura metel shows epipetalous condition. The flowers are also divided into actinomorphic, zygomorphic, and asymmetric flowers depending on the physiological structure.

Now, the flowers belong to the family fabaceae are zygomorphic that means they are biletral symmetrical structure and bisexual.
- They comprises five petals means, polypetalous, the outermost posterior petal is large, along with two lateral petals and the two innermost anterior petals that unit and form a boat-like structure termed as carina.
- They have vexillary aestivation or the descending petals. Stamens are 10, united through their filaments and form two groups that are termed as diadelphous, the placenta is marginal that means it forms a rigid structure in the ventral side and in the two ventral rows the ovules are arranged. And all these characters are observed in Pisum.

Thus, the correct option is ‘A’. Pisum.

Note: Actinomorphic flowers are radially symmetrical in structure so they can be bisected into two equal halves in one or more vertical planes by forming mirror images. The iridaceae flowers are actinomorphic in nature as they are radially symmetrical.