Trees are also entangled with politics. In “An Otherworldly Species: Joshua Trees and the Conservation-Climate Dilemma” historian Thomas M. Lekan discusses what he considers a false choice between climate protection and conservation.

We know where trees grow, but what about ideas? Writer and literary scholar Samantha Walton used to think of research centers as static offices and corridors, hubs for ideas to cluster and sprout. But at the Landhaus, an eco-farm in Bavaria, it is on walks with other fellows where their “thoughts strung out like threads across the paths” they traversed together.

Dennis L. Meadows on the Future of our Planet.

Louis Warren on “The Ghost Dance Movement.”