Question

The specialized parenchymatous cells which help to maintain pressure gradient in sieve tubes of phloem are​

Answer 1

Answer:

companion cells

Explanation:

EXTRA INFORMATION

One unique thing about sieve tubes is that they do not have nuclei, but still they are living. It is so because they are dependant on adjacent companion cells, which develop from the same original meristematic cell. The two cells, together form a functional unit.

Answer 2

The specialized parenchymatous cells which help to maintain pressure gradient in sieve tubes of phloem are Companion cells.

• Companion cells are one of component of phloem tissue present in angiosperms.
• Seive tubes are long cylindrical tube like structure , with peripheral cytoplasm, a large vacoule; by lacks a nucleus.
• Their functions are coordinated by the nucleus of companion cells.
• They are associated with each other through pit-fields connections in their common longitudinal walls.
• Gymosperms lacks companion cells and Seive tubes. They have albuminous cells and sieve cells.

$\star$ Attached image is of longitudinal section of phloem tissue.