What do we call this tree?

Question

Why "Comment appelle-te cet arbre" instead of Comment appelle-t-on cet arbre" for What do we call this tree?

Accepted Answer

Bonjour Paul,
"Comment appelle-te cet arbre ?" to express "What do we call this tree?" is not correct in French.
"te" is a reflexive pronoun which cannot be placed there in a question.

Comment t'appelles-tu ? = What is your name?
Comment s'appelle cet arbre ? = What is this tree called?
Comment appelle-t-on cet arbre ? = What do we call this tree?

-> the "-t-" is used here to make the sentence easier to pronounce.
See the lesson link below:
Say your name
How to form inverted questions with reflexive verbs in French
I hope this is helpful.
Bonne journée !