The speaker begins with a personal experiment: in the summer of 1968 he becomes a vegetarian, and he gives his reasons in a mock-official list. Some are serious (stop consuming, live like the Third World), and the last, "To do it," is almost a shrug. The first stretch is hopeful and physical. He makes friends with bushes, puts down roots, loves the rain, and leans toward the sun, as if he is turning into a plant.
Then the mood drops. "The merciless sponge of the System" soaks up his experiment. What felt like revelation hardens into routine, and the joy is "vaporized." The word "withering" turns the plant imagery against him. He ends up among "consenting adults," a phrase that suggests he has gone along with ordinary life, whether he wanted to or not. Still, the final lines leave a small spark: he shivers and thrills at rumors of the American Liberation Front. The tone is wry, tired, and a little wistful, with a hint of longing for a more radical life.