"See how the petals close together?" she said, indicating the sealed mouth of the purple iris. "Not any insect can gain access to the tender nectar. The bee has to be strong enough to push the petals apart and push its way down into the tube of the flower."

Using two fingers, she spread the mouth of the iris open. "And, there. See how the iris offers itself to the bee? The insect rubs its belly along this groove, gathering pollen from this flower or leaving pollen from another."

She releases the iris petals, and they close again. She strokes the bright yellow landing strip on the lower petal, the splashed indicator that directs the bees to their landing point.

"Nature rewards the strong and persistent," she says.

She is my doctor. I am her patient.

She is my teacher. I am her student.

She is my law. I am . . .