Populus tremuloides

Trembling aspen or quaking aspen is in the willow or Salicaceae family and is the most widely distributed tree in North America with a native range from Canada to central Mexico.

• Leaves are alternate, simple, nearly round, 4–8 cm in diameter with small rounded teeth, and a 3–7-cm long, flattened petiole, allowing them to tremble in the wind.
• The species is dioecious. Flowers are catkins 4–8 cm long, produced in early spring before the leaves.
• Fruit is a 10-cm string of capsules 6 mm long, each capsule containing about ten seeds, bursting to release them in cottony fluff.
• Bark is relatively smooth, coloured greenish-white to gray, and is marked by thick black horizontal patches of various sizes and prominent black knots.