"What are they all doing up there?" wondered the Zurich Tagesanzeiger. "It's probably a forgotten popular sport," suggested Der Spiegel. There was even speculation about the "secret sex life of trees." One thing is certain: Jochen Raiss's Women in Trees, published by Hatje Cantz in 2016, immediately became a bestseller. Perhaps it happened simply because the evident happiness felt by these women (who may have simply been in the mood to climb a tree) is palpable to us all.

Women in Trees made us happy--and hungry for more. So Hatje Cantz asked the obsessive...