Question

In a twiner, the twining structure is
A Tendril
B Spine/thorn
C Curved hook
D Sensitive stem

Answer 1

The plant stem is one of the main structural axes of the plant. It is the important aerial part of the plant and it provides support to the plant and keeps it upright. It bears the other important parts such as the leaves, fruits and the flowers. The stem can be erect or weak in nature.

Complete answer:
A tendril is a short whiplike or threadlike strand that grows from a stem's node and allows a vine or other plant to climb. It could have stem tissue or leafstalk tissue in its anatomy.
Technically, the spine is a modified, sharp-pointed leaf. The spine is in the relative position of a leaf because it has a bud in its axil. Because they are modified, sharp-pointed stipules at the base of a leaf, some spines are called "stipular spines."
Thorns are a type of axillary shoot system in which the leaves are reduced and die fast, while the stems are severely sclerified and only grow for a short time. The plant's thorns appear to defend it from herbivores.
The hook is a tubular structure made up of only one type of protein, although it is curved. It must be both flexible and torsionally rigid in order to execute its purpose. It is unknown what molecular mechanism allows chemically similar subunits to produce such a dynamic shape.
Twiners are climbing plants with a weak stem for this reason. They usually coil around external strongholds such as ropes, rods, and the like. External assistance is critical for them. Because their shoots are touch sensitive, they may readily climb up.

So, the correct answer is option D.

Note: Twiners adore ropes and rods around which they may wound their primary shoot. This is good for many twinners, such as the annual continuous bloomers. However, subsequent major shoots must be unwound and attached parallel to the wire ropes in the event of aggressive twiners, as stated for wisteria.