Fig. 15.1-4. Transverse section of wood of Juniperus ashii (juniper, a conifer). Being a conifer or softwood, this juniper has wood whose axial system contains only tracheids. Parts of five annual rings are present in this micrograph; the center annual ring is wide with many cells in each row because the vascular cambium was active for a long time due to good growing conditions. The annual rings produced just before and just after the center ring are much narrower due to poor growing conditions in those years and the vascular cambium produced fewer cells.