Question

What is holdfast? What is its use? Mention the species of spirogyra having holdfast.

Answer 1

Hint: The plant body is unbranched filamentous, with cylindrical cells positioned end to end, green-colored. There is no basal distinction in free-floating species, while in other sedentary species, the basal cell is altered.

Complete Answer:
- Free-floating freshwater algae that occupy rivers, ponds, lakes, streams, ditches, etc. are typical spirogyras. There are many common names for Spirogyra, like water silk, blanket weed, mermaid tresses, etc.
- It grows in length to several centimetres and in width to 10-100 μm. Worldwide, there are around 400 recognised species of Spirogyra. Because of the existence of an underlying mucilaginous sheath, they are rod - shaped and slippery in nature; they are also called pond silk or pond scum.
- The basal cell of the aquatic plant Spirogyra is altered in some species. The modified cell is known as the holdfast, which allows the plant to bind to the substratum. The cell permits the plant to be bound to a fixed surface.
- The examples of the Spirogyra species that have the holdfast for the adhesive are Spirogyra dubia, S. rhizoids, and S. fluviatilis.

Note: The increase in filament length of Spirogyra occurs by ordinary divisions of cells and subsequent development of individual cells, each of which-further divide. Vegetative and sexual, Spirogyra recreates. Asexual reproduction, in this case, is lacking.