YA Reincarnation and Monkey puzzle tree. Read in 1980's.

[AR]

Hello, I'm looking for the title of a book that I read in the 1980's
It is a young adult book
English or British publication
The plot involves a monkey puzzle tree
In the book the main character, a girl travels back in time or remembers her reincarnation
The cover illustration showed a black tree

[Rainbowheart]

Was the girl a teenager or a younger child?

Can you remember how the monkey puzzle tree factored into the story?