Trees on Hillside

I sa this lone tree on one of my horse rides. I thought it looked

nice against the background hills.

I like the tones of green in this photo, but maybe because of that the main subject (in my opinion that tree) somewhat merges with the background.

It would be interesting to try this shot portrait instead of landscape using the tree as subject and the hills and field as the background due to the various tones for a rainbow effect. As it stands, the right half adds little of interest for me.