Some plants store energy in swollen underground structures. A tuber is a thickened stem or root that holds reserves of starch and nutrients. Potatoes are stem tubers; dahlias and sweet potatoes are often classed as root tubers. The stored food fuels new growth when conditions improve.

Tubers bear buds or eyes from which new shoots emerge. Gardeners propagate many tuber-forming plants by dividing the tubers, ensuring each piece has at least one viable bud. Planting depth and soil drainage influence success and storage quality.

After the growing season, some tubers are lifted and stored dry and cool for replanting. Others remain in the ground in mild climates. Understanding whether a plant forms tubers helps with both cultivation and propagation decisions.

• Thickened underground storage organ
• May be modified stem or root
• Stores nutrients for new growth
• Often divided for propagation