Who is Dede and what are her symptoms. We need more context
The primary source of stem thickening in plants is the vascular cambium. It is a plant tissue located between the phloem and the xylem and in the root of a vascular plant. It is the source of secondary growth or the radial growth of the stem of a plant.
Every plant organ is adapted to its function. For example, leaves that are big and flat absorb plenty of sunlight for photosynthesis. Long roots keep a tree stable and take water from deep in the soil. Some plants have unusual adaptations.
