1. Secondary roots develop from the pericycle which is inside endodermis.
2. Protoxylem is situated close to pericycle in root.
3. Endodermis have suberized layer Casparian strip which forces water to move in the symplast so that it can enter the vascular xylem.
4. Since secondary roots originate form pericycle, they bypass the Casparian strip.
5. Therefore, a direct pathway to xylem and phloem is available without moving into symplast.
