Question

Stem tendrils occur in
a. Smilax
b. Gloriosa
c. Vitis
d. Lathyrus

Answer 1

Hint: The stem is generally green in colour at the initial stage but later it becomes woody and dark brown. It is differentiated into nodes and internodes. The stem of some plants is modified to perform different functions to help plants to adapt to the present environmental condition. Some of the modifications occurring in the plants are: - the underground stem, stem tendrils, thorns and sub-aerial weak stem.

Complete answer:
Tendril is a slender threadlike appendage of a climbing plant, often growing in a spiral form that stretches out and twines round any suitable support. They provide support to the weak and tender stem. Tendrils are formed as modifications of:
• Entire leaf- leaf tendril e.g.m Lathyrus sativus.
• Leaflet- Leaflet tendril e.g., Pisum
• Petiole- Petiolar tendril e.g., Clematis
• Stipule- stipular tendril e.g., Smilax
• Leaf apex- Leaf apex or tip tendril e.g.,Gloriosa
• Inflorescence- Inflorescence tendril e.g., Antigonon
• Stem- Stem tendril e.g., Vitis

Hence, the correct answer is option (B).

Additional information:
The stem bears buds which may be terminal or axillary. A bud is defined as the young, immature, underdeveloped, compact shoot. The buds present on the stem are of two types namely
• Terminal bud: The bud present at the tip of the stem is called a terminal bud. The growth of the stem and its branches is accomplished through the terminal bud.
• Axillary Bud: The leaf makes an angle with the upper part of the stem. The angle made between the leaves and the upper part of the stem is called the axil.

Note: In some plants, the axillary buds present on the stem modify to form tendrils. Passiflora is the example of stem tendril from the modified axillary buds. Vitis is an example of modified apical bud stem tendril. Other examples include cucumber, pumpkins, watermelon etc.