Difference Between Protoxylem and Metaxylem | Protoxylem vs Metaxylem

The key difference between protoxylem and metaxylem is that protoxylem is the first formed primary xylem which has smaller cells, especially narrow vessels and tracheids while metaxylem is the later formed primary xylem which has larger cells, especially wider vessels, and tracheids.

Xylem is one of the two types of vascular tissues in plants. Xylem conducts upward movements of water and minerals from roots to the other parts of the plant. It is a tube-like structure containing different types of specialized cells including vessel elements, tracheids, parenchyma, and fibers. There are two types of xylems as primary xylem and secondary xylem. Primary xylem develops during primary growth. Furthermore, primary xylem has two parts: protoxylem and metaxylem. Both protoxylem and metaxylem originate from the pro-cambium during the primary growth. Protoxylem originates first, and metaxylem originates after the protoxylem.


1. Overview and Key Difference
2. What is Protoxylem 
3. What is Metaxylem
4. Similarities Between Protoxylem and Metaxylem
5. Side by Side Comparison – Protoxylem vs Metaxylem in Tabular Form
6. Summary

What is Protoxylem?

Protoxylem is the primary xylem that develops first during primary growth. Protoxylem matures before plant organs complete their elongation. In a stem, protoxylem is located towards the outside. It consists of smaller cells. In other words, it contains narrow vessel elements and tracheids. Hence, the lumen of the cells is narrow.