Vascular Cambium

Plants exhibit both primary growth, as well as secondary growth. For primary growth the plant elongates, growing out of the soil and towards the sun. This type of growth is fairly rapid in order to maximize photosynthetic output. Secondary growth is when the plant widens. In order to do this, the plant requires a layer of tissue called the vascular cambium. The vascular cambium is between the interior xylem and exterior phloem. This growth forms layers of secondary vascular tissue that keep the phloem and xylem in the correct place. These rings can be counted to determine the age of the plant.