[From introduction] Range management specialists have become increasingly concerned in the past few decades with the competition between species produced by the invasion of shrubby plants into grassland ranges. Big sagebrush, Artemisia tridentata Nutt., is a widespread shrub dominant over large areas of the western United States. It occurs primarily on sites that are capable of growing, or have grown, a grass cover and is thus an invading species. Complete evaluation of the ecological status of the species in terms of succession requires analysis of annual growth layers (the so-called "rings") to determine the age of a given plant and the growth potential of the site. The objective of this study has been to evaluate big sagebrush throughout the southern limit of its distribution with respect to structure and rate of annual lateral growth of the stems with a view to application to ecological problems of range management.