This tale of a shrinking girl is both engaging and imaginative. In the spring, Mary Margaret plants a tree in her backyard. Weary from the task, she finds herself getting small, while the tree grows up before her eyes. She climbs into the tree and, during the passing seasons, observes its natural processes, both pleasant and unpleasant, from watching a nest of birds hatching to Mary Margaret's almost becoming another bird's meal. Winter comes, and Mary Margaret rides a leaf to the safety of a cave, where she hibernates until spring. That's when she takes root and becomes a tree. The reverie is broken when her mother calls her in for dinner; her tree-planting gear is still beside her. Drawson's fetchingly flighty pictures are the ideal counterpoint to the serious theme. Mary Margaret takes some amazing transformations in stride, and whether she's curled up in hibernation or bent over her dinner at the end, she's a heroine who doesn't merely accept her lot, but makes the very best of it. (Picture book. 4-8)