Secondary xylem is the type of xylem formed from secondary growth. In comparison, the primary xylem forms during primary growth. Because of this, the secondary xylem is associated with lateral growth rather than vertical growth as in the primary xylem.

How is the secondary xylem formed?

Secondary xylem is formed during secondary growth from vascular cambium.

Where does secondary xylem originate?

In woody roots the vascular cambium (the lateral meristem that gives rise to secondary phloem and secondary xylem) originates in the pericycle as well as in the procambium; the procambium is the primary meristematic tissue between the primary phloem and xylem.