The key difference between sieve tubes and companion cells is that the sieve tubes are the phloem sieve elements that conduct food in angiosperms whereas, companion cells are the associated cells of sieve tubes. Moreover, sieve tubes have pores in the transverse walls while companion cells do not have pores.
Phloem is one of the two types of vascular tissues. It is the vascular tissue that conducts food from photosynthetic parts to other parts of the plant. Phloem consists of different cells. Among them, sieve cells and sieve tubes are the two types of sieve elements that carry out food transportation throughout the plant. Sieve cells are present mostly in seedless vascular plants and gymnosperms. However, sieve tubes are present only in angiosperms. Sieve tubes are associated with living companion cells. Moreover, these sieve tubes and companion cells are unique to angiosperms.
1. Overview and Key Difference
2. What are Sieve Tubes
3. What are Companion Cells
4. Similarities Between Sieve Tubes and Companion Cells
5. Side by Side Comparison – Sieve Tubes vs Companion Cells in Tabular Form
What are Sieve Tubes?
Sieve tubes are the sieve elements present in angiosperms. They are elongated large cells that have pores in their transverse walls. Moreover, at the young stage, sieve tubes have a nucleus. But with maturity, the nucleus disappears from the sieve tube cells. They have a few number of mitochondria. However, they lack ribosomes, unlike companion cells.