the time we realize the confusion, he has given up and cheerily sends us on our way, unfined. (I suspect that Brad, who is in the passenger’s seat, has used the Jedi mind trick.) The last forest on the trip is back in the clouds, high on the slopes of another volcano, Barva. We collect leaf and wood samples in the general area of a gentraso that Brad surveyed in the past. Hiking out of the woods with our final bags of specimens and our final crop of chigger bites, a male quetzal flies across our path, pursuing a female.

I think of Gentry, who would have marched through this forest putting a Latin name to every tree. Then I think of the message of the gentrasos: All that seems to differ between forests is the number of species that live there. Trees across the world are remarkably constant in the ways in which they use energy and grow, and this uniformity leads to a constancy of structure in the world’s forests through space and time. So why is life diverse? If all living things use energy in the same way, why do they come in so many different types? If life is a struggle for energy, why does the cloud forest around me contain scores of tree species, rather than just one that has managed to outdo all the others? If you’ve seen one tree, why haven’t you seen them all?