Question

The fibre of sunn hemp is obtained from ……….
A. Leaf
B. Mesocarp
C. Phloem
D. Testa

Answer 1

Hint: Bast fibres surrounding the stem obtained from herbs cultivated in agriculture as for instance flax, hemp, etc.. The fibers are nonliving cells that provide mechanical support and give strength and rigidity to the organ.

Complete answer: Phloem is the chief conducting tissue of vascular plants responsible for translocation of organic solutes.
The phloem is composed of several kinds of cells
The basic components are:
(i) sieve elements,
(ii) companion cells
(iii) phloem parenchyma, and
(iv) phloem fibres
Phloem fibres are also called bast fibres and mostly occur in secondary phloem.
The fibres of primary phloem have both cellulose and lignified thickenings. The fibres of secondary phloem are elongated lignified cells with simple pits. The ends of these cells may be pointed needle like or blunt.

So, the correct answer is “Option C”.

Additional Information: 1. Sieve elements: It is the main component of the phloem.
The main functions of the sieve elements are the translocation of organic solutes.
2. Companion cells: These are living cells usually always associated with the sieve tubes. In primary phloem, the companion cells are formed by unequal longitudinal division or procambial cell. Each companion cell is a living cell with a thin cellulose cell wall and protoplast. It posses all the important cellular components.
3. Phloem parenchyma: These are living parenchymatous cells present as components of phloem.
The cells are elongated with rounded ends and posses cellulose walls. These cells are living and store food reserves in the form of starch and fats.

Note: Sunn hemp ( Crotalaria juncea) is mainly grown as a fibre crop that was much used in the traditional manufacture of ropes, strings, twines, floor mats, and finishing nets.
Sun hemp fibre can be used as a protein source to supplement poor quality roughage.
The crop is grown for green manure as a soil improver. Sun hemp is locally used as fodder.