Leaf veins. Macrophotograph of leaf veins in a nasturtium (Tropaeolum majus). A radial pattern of leaf veins branches from the leaf stalk in nasturtium leaves. These veins then branch further to produce an elaborate network of vessels that supply the leaf with water and minerals and carry food (carbohydrates) out of the leaf. The net-like branching arrangement distinguishes dicotyledonous flowering plants from the monocotyledons, which have narrow leaves and parallel veins.