There appears to be a general presumption among ecologists used to viewing the easily observable aboveground parts of plants (such as the leaves of deciduous trees) that roots, invisible in the soil, must also live for much of a growing season. Despite the existence of a number of large walk-in rhizotron facilities in several parts of the world, few data on the longevity of roots have been published, and until the building of the University of Michigan Soil Biotron, no substantial facility existed to record data on root dynamics for noncrop species. Against this background, a new paper by Hendrick and Pregitzer is a welcome addition to the literature. Their paper introduces the use of mini-rhizotrons for ecological studies and presents information on root production, longevity and dynamics for roots of the maple Acer saccharum, a noncrop species. Both of these represent significant inoovations for plant and community ecology.