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.