Question

Tendrils are found in the following plants. Identify whether they are stem tendrils or leaf tendrils.
(a) Cucumber
(b) Peas
(c) Pumpkins
(d) Grapevines
(e) Watermelons

Answer 1

Hint: These are threadlike specialized plant organs which are characteristics of climbing plants and are used to anchor and get support for the plants with soft and tender stems. They get support by climbing to the nearby plants or objects with the help of specialized organs.

Complete answer:
Tendrils found in cucumber, pumpkins, grapevines, and watermelons are stem tendrils and that of a pea plant is leaf tendril. Tendrils are specialized slender threadlike organs in plants growing in a spiral manner, that stretches out and twines around any living or non-living object to provide support to the plant. They are modified forms of leaves, leaflets, leaf tips, or leaf stipules as in pea plants, Pisum sativum, and they may also be derived from the stem as in cucumber, pumpkins, grapevines, and watermelons.
-Tendrils are strong enough to support the weight of the plant.
-Some tendrils produce terminal enlargements that flatten when coming in contact with a firm surface and secrete an adhesive for firmly cementing the tendril to the substrate.
-Tendrils do not have a lamina or blade, but they can produce food for plants by the process of photosynthesis.
-Tendrils formed from modified shoots are called stem tendrils, modified leaves, or auxiliary branches are called leaf tendrils.
-Tendrils are very sensitive to chemicals and can determine the direction of growth of the plant.
-Tendrils also help in cellular invasion by parasitic plants to derive food from the body of the host.
-Tendrils found the suitable host by touch or thigmotropic responses by tendrils in flowering plants.

Note:
-The most comprehensive and earliest study on tendrils was done by Charles Darwin. His work was published in 1865 in his book 'On the Movements and Habits of Climbing Plants'.
-Thigmotropism is a directional growth movement resulting from the touch stimulus which occurs as a mechanosensory response. This is mainly found in twining plants and tendrils.