Final answer:
Land plants developed vascular tissue to strengthen the conducting cells and help them stand erect without water.
Step-by-step explanation:
Land plants developed vascular tissue to strengthen the conducting cells and help them stand erect without water. Vascular tissue consists of xylem, which conducts water and minerals absorbed from the soil up to the shoot, and phloem, which transports food derived from photosynthesis throughout the entire plant.
The cells walls of xylem are reinforced with lignin, which adds strength to the tissues and prevents water seepage.