Discuss all structural features of xylem which you expect to find in plants that grow in tropical forests
Plants that grow in tropical forests need to have adaptations in their stem structures to survive in hot and humid conditions. In particular, the xylem tissue of these plants must be specialized to transport water efficiently from the roots to the leaves while minimizing water loss through evapotranspiration. Below are some of the structural features that you can expect to find in the xylem of tropical forest plants:
1. Large diameter vessels: Tropical forest plants often have wider xylem vessels compared to plants from temperate regions. This allows for greater water flow and a larger surface area for gas exchange.
2. Secondary growth: Many tropical forest plants are woody and undergo secondary growth, which produces thicker stems and allows for greater water transport capacity.
3. Tracheids: Along with vessels, tracheids are the other type of water-conducting cells in xylem. In some tropical forest plants, tracheids are more abundant than vessels, as they offer greater resistance to cavitation (air bubbles forming in the xylem).
4. Xylem fibers: These are supportive cells that provide mechanical strength to the stem. In tropical forest plants, fibers may be more lignified (containing more lignin, a structural polymer) and thicker-walled than in temperate plants.
5. Double helix arrangement: Some plants (e.g. lianas) in tropical forests have a unique double helix arrangement of their xylem fibers, which allows them to resist twisting and maintain their shape as they grow around trees or other structures.
6. Xeromorphic adaptations: In drier regions of tropical forests, some plants may develop xeromorphic adaptations in their xylem, such as smaller vessel diameters or thicker cell walls, to conserve water.
Overall, the xylem of tropical forest plants must be highly efficient in transporting and conserving water, while also providing mechanical support. These structural adaptations allow tropical forest plants to thrive in their challenging environment.