{Growth - shoot and root - explained}
Unlike many babies out there, our little angel grows continuously!
This is because of his meristems. These populations of undifferentiated cells can continually undergo mitosis and produce new cells. However, our baby needs to make sure that some of these cells become specialized so they can perform specific functions that he needs. Thus, when his meristematic cells divide, some of the daughter cells remain in the meristem, and some differentiate. This allows the meristem to continually produce undifferentiated cells via mitosis, and for some of the newly-produced cells to become specialized for distinct structures and functions.
Our sweetheart has two types of meristems: apical and lateral. His apical meristems are located at each root and shoot tip. Thus, when our little guy's apical meristematic cells divide and become differentiated to a specific function, our baby himself will enlarge, and his root and shoot tips will extend outward from the body. It is just so cute when he discovers something new! Lateral meristems (also called cambium) are cylindrical, running the entire length of a root or stem. Only one layer of meristematic tissue makeup the lateral meristems, and from that tissues cell will divide in a way that makes our little baby grow wider in both his roots and shoots. Two different types of lateral meristematic tissue can be found in our baby: vascular cambium and cork cambium.
All of this is extremely important in how our little guy continues to grow. And as he gets bigger, we can attribute certain meristematic functions to certain types of growth. Apical meristematic growth represents the process of primary growth. As apical meristematic cells continually divide and become specialized, the length of the root and shoot systems will continually increase. Furthermore, it is important to remember that when considering the entire structure of the plant, those cells that formed from the apical meristem makeup the primary plant body, the foundation of our little man. As roots and shoots increase in length from apical meristematic tissue, our boy's reach will increase as well, allowing him to have an increased ability to absorb photons and acquire carbon dioxide, water, and ions. Without such increased ability, our little angel wouldn't be a healthy young whipper-snapper as he is now!
As for our sweetheart's lateral meristematic tissue, or cambium, secondary growth is represented. Vascular cambium - a ring of meristematic cells located between the secondary xylem and phloem in the stems - and cork cambium - another ring of meristematic cells located near the perimeter of the stem - in our baby both function to make our boy's body wider. This secondary growth increases the amount of conducting tissue available, and provides a level of structural support that is necessary for primary growth to continue.
Primary and secondary growth work together, just like us, the loving parents of our sweetheart!
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