Why does Bud think ideas are like trees?
Bud thinks that ideas are like trees because they have the potential to grow, just like trees grow from tiny seeds.
To Bud, an idea is like a seed. It has the potential to grow into reality. He relates that the idea of Herman E. Calloway being his father began when he first spied one of Herman E. Calloway's flyers. That small idea soon burst "out of the dirt" when Billy Burns teased the boys at the Home.
Bud remembers how Billy teased him and his friends, challenging them to reveal who their parents were. Billy Burns bet a nickel that none of the boys could reveal who their fathers and mothers were. Upon hearing this, Bud told Billy that his father was Herman E. Calloway. Bud maintains that this is how the idea of Herman E. Calloway being his father was born. That idea then grew and became the impetus for him to travel across the state of Michigan. So, to Bud, ideas are like trees because they have the potential to grow into reality.