Pulvinuli, also known as pulvini, is a term used in botany to describe specialized structures found in certain plants. These structures are small, pillow-like swellings that occur at the base of leaf stalks, veins, or other plant parts. They are typically composed of parenchyma cells, which are the most common type of plant cells responsible for various functions.
Pulvinuli serve multiple purposes within the plant. One of their main functions is to provide mechanical support. The cushioning nature of these structures helps to absorb mechanical stress or strain caused by wind, gravity, or other external factors. They also aid in maintaining the plant's posture by controlling the movement of certain plant parts.
Furthermore, pulvinuli play a vital role in plant movements, particularly in nyctinastic or sleep movements. Nyctinasty refers to the diurnal rhythmic movements exhibited by certain plants, wherein their leaves or flowers fold or close during nighttime or under darkness. The pulvinuli are responsible for regulating these movements by controlling the turgor pressure and fluid distribution in the cells surrounding them.
Overall, pulvinuli contribute to the adaptive capabilities of plants, allowing them to respond to environmental changes and optimize their growth and survival. By providing support, regulating movements, and facilitating responses to external stimuli, these specialized structures play a crucial role in the functional and physiological processes of plants.
