Plant stem cells are primarily found in meristematic tissues, which are regions of actively dividing cells responsible for plant growth. The two main types are apical meristems and lateral meristems.
Apical Meristems
Apical meristems are located at the tips of shoots and roots. They are responsible for primary growth, which is the increase in length of the plant. Within apical meristems, there are more specialized regions:
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Shoot Apical Meristem (SAM): Found at the tip of the shoot and gives rise to leaves, stems, and flowers. The SAM maintains a population of stem cells that divide and differentiate into various plant organs.
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Root Apical Meristem (RAM): Located at the tip of the root and responsible for root growth. The RAM is protected by a root cap.
Lateral Meristems
Lateral meristems are responsible for secondary growth, which is the increase in the girth or width of the plant. There are two main types of lateral meristems:
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Vascular Cambium: This meristem produces secondary xylem (wood) and secondary phloem (inner bark), increasing the diameter of the stem and root.
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Cork Cambium (Phellogen): This meristem produces the periderm, which replaces the epidermis as the outer protective layer of the stem and root. The periderm consists of cork cells, cork cambium, and phelloderm.
In summary, plant stem cells are primarily located within apical and lateral meristems, facilitating both the lengthening and widening of the plant body. They retain the capacity for self-renewal and differentiation into specialized cells.
