"Bruma, yes, a fine city. I traveled through it on my journey to Skyrim. It would do well for this new garden." Ravari looks over the goods he's chosen, and her ears droop briefly. He calls her friend and she takes so much money from him...

So she'll add a book to rebalance the scales, just a bit. "This will help you learn about the new specimens, I believe." Herbalist's Guide to Skyrim is exactly what it claims to be.