Quaking Aspens

Why were they named 'quaking' aspens?  I would say they more shiver, or shake, or quiver when the wind blows.  No matter their name, aspens are a symbol of home for me.  They are beautiful and welcoming.  Fun fact for the day:  aspen trees in the same grove usually are the same organism.  The shared root system has simply sent up multiple shoots as it expands under ground over time.