Stands of bright gold aspen (Populus tremuloides) shimmering in the sunlight are a spectacular sight, so it is no surprise that many people plant aspen in their home landscapes. Aspen are fast growing and relatively short-lived relatives of cottonwoods and poplars. Ranging from 40 – 65 feet tall, they have a smooth white trunk and bright green, heart-shaped leaves. Female trees produce 2-inch catkins that develop into tiny long, narrow cones.