What do vascular plants use to grow new plants?

Vascular tissues include xylem and phloem. They allow plants to grow tall in the air without drying out.

because the light is a great source of energy for the plants to survive. (i hope this )

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.