Question

In hook climber Artabotrys, the hooks are modified
A. Petioles
B. Axillary shoots
C. Leaves
D. Inflorescence axis

Answer 1

Hint: The aerial portion of the plant is called the stem. It has nodes and internodes and it bears vegetative buds for vegetative growth of the plant, and floral buds for reproduction, and ends in a terminal bud. It plays different roles in plants such as provides support and bears leaves, flowers and fruits.

Complete answer:
Artabotrys hexapetalus is an ornamental plant which grows in the tropical climate. It is known as "climbing ylang-ylang. This plant produces specialized hook-like structures. The hook-like structure in Artabotrys is the inflorescence axis or peduncle is modified into the hook. The hooks are stiff curved thorns which help for climbing.

Thus, option D. Inflorescence axis is the correct answer.

Additional information:
Other climbers are:
> Stem climbers: These climbers lack specialised structure for climbing but the stem itself coils around the support. For example, Convolvulus, Dolichos, Clitoria, Quisqualis.
> Thorn climbers: Thorns are modified stems that are meant for climbing as in Bougainvillea and Carissa.
> Lianas: Woody stem climbers are lianas. They twine themselves around tall trees to get light as in Hiptage benghalensis, Bauhinia vahlii.
These are the aerial modifications of the stem which provides support and protection to the plants.

Note:
Floral stalks or pedicels of Artabotrys produce a curbed hook. This hook is the modification of the inflorescence axis that helps the plant in climbing.The pedicels or floral stalks of Artabotrys are modified into stiff curved thorns or hooks for helping in climbing. Hook is formed by peduncle in Uncaria gambir. It climbs with hooks formed by the inflorescences. The pedicel develops into hooks for climbing.
Artabotrys hexapetalus have long weak stems and produce special organs for attachment for climbing over a support. Climbing helps to display the leaves towards sunlight and to position the flower for effective pollination.
These plants produce specialized hook-like structures which are the modification of various organs of the plant. In Artabotrys inflorescence axis is modified into a hook. In calamus (curved hook) leaf tip is modified into a hook. In Bignonia unguis-cati the leaflets are modified into curved hooks. In Hugonia the axillary buds are modified into hooks.