What Is a Plant Vein?
Just as animals have vessels that carry materials throughout their bodies, plants have veins for the transportation of nutrients, including water. Plant veins are also sturdy enough to act as a support system and keep leaves open for photosynthesis -- the process through which plants make food. Plants have a vascular system throughout their roots and stems, but the system's veins are most visible in leaves.
Veins are distributed either in a netlike or parallel formation. Narrow and needle leaves typically have a parallel vein structure with a main vein or veins extending from each leaf's base to its tip. Leaves of broad-leaf plants have one of two types of netlike veins. A pinnate leaf, for example, has a dominant, central vein with other vessels branching to the vein's sides. A palmate leaf, however, has several large veins originating from the leaf's base.