Adapting Trees

Trees, Who told you?
The time to dress your leaves
In vivid yellow and red
And send them to Mother Earth;

Trees, who told you?
That the icy cold is approaching;
How do you know the time?
To shed or grow new leaves;

Trees, who told you?
I believe you exist since before man
I assume you know not the months
For the calendar is designed by mankind;

Behold trees! You are awe-inspiring!
I salute thee indeed! Know ye the times
To bloom, yield and shed, ever gladdening
Yet stand humble and serene!