I found this leaf in the woods upstate and what I loved about it was how it was in the midst of transformation--turning from green to gold to yellow. I noticed that the lower edge near the stem got yellow before the top. Leaves change color when days get cooler and shorter and the auxin production ends, so the chlorophyll breaks down, and in the birch leaf (like this one, maybe Betula alleghaniensis or Betula lenta) the carotene shines through as yellow.
Photographing the actual leaf next to my drawing pointed out my shortcomings in a big way. I realized that I had made the base of the leaf too narrow. I had to adjust my drawing. I made my yellow/gold a little dark, but color depends on light and in some lights, the leaf looked darker than in others. I adjusted but dark over light can get muddy, so I had to be careful. The paper also started to curl from the water. This simple alternate leaf has a short stem, toothed edges, and veins that meet and radiate from a central vein. Here it is in my sketchbook. I knew I could not get all the details right, but drawing nature is about that—details, details, details. I draw to learn.