What is a stem?

• A stem is an organ that performs the function of transporting water/minerals to areas of photosynthesis, as well as supporting leaves and smaller stems.

• Stems tend to grow negatively gravitropic (away from gravity) and are also phototropic (growing toward the light). Rhizomes grow in a diagravitropic manner (perpendicular to gravity)

• Buds are located along the stem to allow for the creation of new shoots and branching. Buds are not found in roots or leaves.

• Stems tend to be cylindrical in shape, therefore round in cross-section, although some stems can be square (e.g. mints) or triangular (e.g. sedges) in cross-section

  • N.B. some photosynthetic stems can be two-dimensional and leaf-like called cladophylls. These stems would still have axillary buds, not found in leaves, and the anatomy of leaves and stems would differ.

• Stems are some of the most ancestral organs found in land plants, especially rhizomes that creep along the soil, also creating upright stems that grow toward the sun

  • N.B. rhizomes appear to be quite root-like but these stems would still have axillary buds, not found in roots, and the anatomy of roots and rhizomes would differ.

• Some ancestral plants, such as mosses, have stems that lack vascular tissue, but these stems can still move water and support leaves.