First off it does help to have a few books on the how too's of herbal prep of harvesting , production of herbs , trees etc. so I will list just a couple
The Herbalists Way is a must have
The Herbal Medicine Makers Handbook
Herbal Body Book
Then there are the books that I oh so love that have helped me learn more to acknowledge plants as teacher
Sacred Plant Medicine
The Meaning of Trees
The Spirit of Trees
Canadian Forest Tree Essences
Plant Spirit Healing
Plants of the Gods
All the Plant Books by the poetic Dale Pendell
Language of Flowers
Folklore and Symbolism of Flowers , Plants & Trees
The Real Witches Garden
Hygieia a Woman's Herbal
There are also many sources now offering courses in both the spiritual & medicinal workings with the plant world . Many can be very pricey though and as well many are online .
I personally feel once again it best to pray and be patient and look to what might be offered locally . Either from a herbalists shop or local community groups including Indigenous peoples of your area .
So below I'll just list a few online sources for teachings online and hands on .
Susun Weed Herbal Courses
The Foundation for Gaian Studies Stephen Buhner
Anima Healing Arts