Question

In Heartgold how do you get past the mysterious, whispering tree on route 24 ,I think.

Answer 1

In Goldenrod city there should be a flower shop. Talk to the people in there and you get a watering can. Then interact with the tree

Answer 2

Beat the golden rod gym leader then go to the flower shop next door they will give you a watering can which will make the tree move which you find out to be a level 20 sudowoodo