Family Tree by Sheri S. Tepper
Police officer Dora Henry talks to the trees, and they listen. They also provide her with fruit out of season and guard her bicycle. Why they do these things, she's not sure, but she doesn't have time to worry about it: three geneticists have been murdered and clues are in short supply.

She's also going through a painful divorce from her abusive husband, Jared, after two years of sterile, sexless marriage--and Jared has vowed that he won't let her go and has begun stalking her. The trees, meanwhile, are springing up everywhere, ripping up streets, kidnapping unwanted babies and acting like sentient beings. Dora's story represents only half of what's going on in this tale, however. In a parallel narrative set 3000 years in the future, Opalears, a young slave in a quasi-Arabic society, accompanies her master on a quest to seek interpretation of an ancient prophecy. As they travel, they are joined by others on their own quests. Eventually, Opalears and her companions also run into sentient trees.

When the future peoples come into Dora's world, everything becomes clear. Dora must work with the future peoples to save the future and maybe even herself.

It's been a long time since I read any of Tepper's work. It deals with many controversial topics such as controlled populations, animal testing and intelligence, and deforestation. She is an excellent storyteller and while not one of her best works it is still thought provoking.

Tepper wrote as B. J. Oliphant & A. J. Orde in the 1990's writing two different mystery series.