What is the term for small openings in stems for gas exchange?

The term for small openings in stems that facilitate gas exchange is "lenticel." Lenticels are specific structures found on the surfaces of stems and some roots, allowing for the exchange of gases such as oxygen and carbon dioxide between the internal tissues of the plant and the external environment. They are crucial for the respiration of parts of the plant that are above ground and may be in contact with the air.

Lenticels are typically formed by the loosening of cells in the outer layers of the plant, creating small openings that remain functional throughout the life of the stem. The presence of these openings helps ensure that essential gases can enter and exit, supporting metabolic processes.

In contrast, aerenchyma refers to a specialized tissue with large air spaces found in some aquatic and wetland plants, aiding in buoyancy and gas exchange. Stomata, on the other hand, are primarily found on the surfaces of leaves, functioning as the pores for gas exchange during photosynthesis, and are not present on stems in the same way as lenticels. The term "vent" is not a standard term used in plant anatomy to describe structures for gas exchange.