Lateral growth in trees frequently begins later than growth in height, but the period of lateral growth is longer. Rates of lateral growth likewise are low at the outset, increasing after a few weeks and then diminishing. In view of the long annual period of lateral growth in trees, deleterious environmental conditions may exercise a pronounced effect on growth. In the wood of trees of temperate regions, narrow and wide growth rings may be observed, marking years characterized by unfavorable and favorable conditions for growth.
The maturation of the newly formed xylem cells leads to the outward movement of the cambium and of tissues like bark external to this meristem. The extent of centrifugal movement of the cambium in a specific growth period is equal to the amount of secondary xylem or wood which has matured in that period.
Growth Phase. Three basic factors affect the growth phase of cell populations: (1) the number of organisms involved—the more parent organisms present, the more offspring there can be. (2) During this period most of the organisms reproduce; few are barren. (3) The generation time is constant—that is, the time it takes for each organism to appear, mature, and reproduce is relatively constant throughout the growth period.
Lateral growth in trees frequently begins later than growth in height, but the period of lateral growth is longer. Rates of lateral growth likewise are low at the outset, increasing after a few weeks and then diminishing. In view of the long annual period of lateral growth in trees, deleterious environmental conditions may exercise a pronounced effect on growth. In the wood of trees of temperate regions, narrow and wide growth rings may be observed, marking years characterized by unfavorable and favorable conditions for growth.