The leaves of the aspen tree are a light minty green, and have an invitingly glossy texture. When coloring the aspen leaves, you might use a combination of grass greens, jade greens, and possibly a few lighter blues, such as robin's egg blue, to create a variety of shades in the leaves. To bring the leaves to life and give them depth, you can use the lightest green shades at the tips of the leaves, a darker green in the middle, and then a few shades of yellow-green to compliment the blues.
The aspen leaves usually grow in clusters, and are arranged in a spiral pattern. To achieve the realistic representation of the tree branches, use light shades of gray and black to add some contrast in the shape of the leaves. Adding some darker accents to the light green leaves will bring out the detail and make it look more like a spiral.
The fruit of the aspen tree is a small, round, hard seed. This seed will be a bright green when ripe, so use a combination of lime green and olive green to give the seed a vibrant, lively colour. These greens can be mixed together or otherwise shaded to achieve the desired colour. For a more realistic look, you can use a light yellow green color to add some highlights to the seed.