Secondary Growth

Secondary growth is characterized by an increase in the girth or thickness of a plant stem or root. Unlike primary growth, which occurs at the tips of shoots and roots, secondary growth involves lateral expansion. It has the following features:

• It is common in dicots and gymnosperms and results in the development of woody tissues.
• Two lateral meristems, the vascular cambium and cork cambium, play key roles in secondary growth.
• The vascular cambium produces secondary xylem (wood) inward and secondary phloem outward. It increases the mechanical support and allow water and nutrient transport.
• The cork cambium produces cork cells that replace the epidermis.It forms the protective bark.
• Annual rings visible in a tree’s cross-section reflect growth patterns influenced by favorable and unfavorable environmental conditions.
• Secondary growth is essential for the development of durable and resilient plant structures.

Anatomy of flowering plants includes stems for structural support and transport of water and nutrients, roots for anchorage and nutrient absorption, leaves for photosynthesis, and reproductive structures such as flowers containing essential organs like stamens and pistils for sexual reproduction. The plant tissues are broadly classified into meristematic (apical, lateral, and intercalary) and permanent (simple and complex). The main functions of tissues include the assimilation of food and its storage, transportation of water, minerals, and photosynthates, and mechanical support to the plant.