For example, a peripheral neuropathy caused by a vitamin deficiency can be treated -- even reversed -- with vitamin therapy and an improved diet. Likewise, nerve damage brought on by alcohol abuse can often be stopped and improved by avoiding alcohol.
2. Vascular tissue - xylem and phloem in leaves form in strands called veins. Xylem forms on the upper side of a vein (on a vertical leaf, on the side next to the stem), and phloem on the lower side (side away from the stem). a. Veins are like a leaf's fingerprint and can be used to identify plants.
The first consists of very small, dark-brown to black spots, less than 1 mm diameter; these give the leaf a sooty appearance and rough texture. The spots may cluster in lines and appear as streaks running diagonally across the leaf, or from the midrib to the leaf edge, often along veins.