Much of the vocabulary of movement- of exhalation and inspiration- reflects the capillary processes of trees. The fractal attenuation of trunks to twigs parallels the circulatory systems of humans and rivers. From above, the Mississippi delta resembles a tree. Histologies from the brain's seat of sensory and motor control look like trees. Subways, highways, sewers, bile ducts and hepatic arteries branch and merge, circulate and drain. The flow is inexorable.

In the woods, as the sun moves, trees draw and redraw their reciprocal forms in shadows on the ground; their canopies filter the sky. After a hurricane, empty pilings stand where houses used to be. Torn and spindled stumps and splintered shrapnel are the forensic remains of trees.

Once I drove a long way to visit a venerable old tree. But I needed a canoe to reach it. Daily, Louisiana cedes ground to rising water. The weather grows ever more unpredictable. In heavy downpours, we say the sky is opening. Wind and water shape us.

The Mississippi clogs with sediment. An artery in the brain obstructs and explodes. Balls of grease block sewers; tar balls sink in the gulf. A fender-bender becomes a bottleneck. The lights under the dock draw the fish, and bait balls circle.

The housing bubble, the sprawl, the fallow subdivisions. Once you build a road, the lumber trucks follow. Young trees, loose-grained, their growth spurts laminated into plywood, sawn into posts lift houses ever higher. Runoff, backflow, effluvia: oil and water mix. The flow is inexorable.