Question

Describe the four kinds of phloem tissues.

Answer 1

Phloem is the complex permanent tissue of the plants. It is involved in the bidirectional translocation of photosynthates and hormones. It consists of the following types of cells:

1. Sieve tube elements: These are arranged in the form of a column to make a sieve tube column. These cells have a thin cytoplasm and nucleus is absent. Their end walls are perforated. These perform the function of translocation of sugars.

2. Companion cells: These are associated with sieve tube elements. They control the metabolism of the sieve tube elements and also transfer photosynthates from the mesophyll to the sieve tube elements.

3. Phloem fibres: These are thick-walled narrow lumen cells that provide support.

4. Phloem parenchyma: These are thin-walled parenchymatous cells that perform storage function.