P waves are a type of seismic waves and they travel through solid, liquid and gas. They are called P waves because they are faster than the S waves and other types of seismic waves.
The p waves being the fastest is why it was named primary (p waves) while the S waves are slower and are referred to as secondary (s waves). These waves don’t start as surface waves but later results in it.
Commensalism is when one organism benefits and the other doesn't benefit and is also not harmed. The tree is helping the orchid and the orchid isn't benefiting or harming the tree.
