I have always loved the beautiful tall Aspen trees - especially in the fall when the green heart shaped leaves turned a beautiful yellow - golden color. But, I did not know that aspen trees produce very few seeds and reproduce or repopulate forests by their massive underground root system, not seeds or pods like most other trees. Aspen trees prefer the cooler climates and they are called "quaking" because of the shape of their leaves causes them to rattle in the breeze - they shake or "quake" when the wind blows through them, especially in the fall when they are bit more brittle. Aspen grow in groves because of their root systems reaching out to similar roots and finally finding open sunny places where they can thrive. They are also easily identified because of their tall, slender white trunks.