The Family Tree — Sheri S. Tepper

THE ONCE FERTILE EARTH OF DORA HENRY'S CHILDHOOD HAS BEEN UNDERVALUED AND OVERDEVELOPED. NOW NATURE, APPARENTLY, HAS DECIDED TO FIGHT BACK.
Police officer Dora Henry is investigating the bizarre murders of three geneticists. Meanwhile, strange things are happening everywhere she turns. Weeds are becoming trees; trees are becoming forests. Overnight, a city is being transformed into a wild and verdant place.

And, strangest of all, Dora can somehow communicate with the rampaging flora.

A potential civilization-ending catastrophe is in the making. The bearer Dora gets to a murderer--and to the truth--the more seemingly disparate events begin to entwine. And the answers she seeks today to the salvation of humankind may lie in afar distant future. . .one which is suddenly much closer than anyone imagines.