Which part of the plant is responsible for providing rigidity?

The xylem is responsible for providing rigidity to the plant. This is because it consists of specialized cells that transport water and nutrients from the roots to the rest of the plant. In addition to its role in water transport, the xylem tissues are lignified, meaning they have a tough, woody substance called lignin that reinforces their structure. This lignification gives support and strength to the plant, helping it to maintain its upright position and withstand external forces like wind.

The other components mentioned do not contribute to structural rigidity in the same way. Phloem is primarily involved in the transport of sugars and nutrients produced during photosynthesis rather than providing support. Chloroplasts are the sites of photosynthesis and play a role in energy production but do not contribute to rigidity. Stomata are small openings on the surface of leaves that facilitate gas exchange but are not concerned with the structural integrity of the plant.