Acorn Naturalists now offers a wide selection of tree limb cross sections. These quality rounds range in size from 2" to 5" across by 1/4"-1/2" thick and allow for clear reading of growth rings. Tree rings vary in size and appearance depending on growing conditions and species variations. Oak species can be easily identified by their characteristic radial rays, pine and walnut and oak show classic seasonal dry/wet ring patterns, walnut shows classic dark-colored center. Tree rounds provide an ideal hands-on resource for introducing students to botany, forestry, dendrology and methods scientists use to determine past climatic conditions. Acorn Naturalists offers a varied selection different tree rounds of both eastern/midwestern as well as western species, Also available is a bark beetle life cycle demonstration kit and two tree round discovery kits (eastern and western).