Don't laugh, he was serious. For many of you, this is a ridiculous question, but to other this part of Muay Thai legends is real. As is the case with most myths, the belief that Thai Boxers train by kicking trees is Based on fact. Thai boxers are known for their painstaking physical conditioning, and in particular, their extremely hard shins.
But contrary to what many believe, this is achieved through the use of very modern equipment. As they condition their bodies with pad drills,

sparring, or exercise, they toughen their shins on the heavy bag. Most Thai boxer begin training between theages of 8 and 12, then being competing professionally between the ages of 16 and 22. After 8 years of kicking the heavy bag every day, their shins are like iron! However, Thai boxers have not always had access to
equipment such as heavy bags, hence, the banana tree. A banana tree is not hardwood like most trees found in the USA. Banana trees have a softer, more plant-like trunk,  which will give a little when kicked.

Additionally, beginning Thai boxers would not start off by kicking a tree with ful force, rather they would start kicking slowly without much power until the shins would eventually toughen to withstand the punishment. Trees are sometimes still  used today for training. Thai boxers kick them with minimal power in order toimprove speed and accuracy. Though, in all honesty, there are those who are capable of kicking trees without any real harm to themselves, this is largely an old practice rendered obsolete by the use of modern boxing equipment.

So in finale, please... DON'T TRY THIS AT HOME WITHOUT Training!