Tendril

In botany, a tendril is a specialized thread-like stem, leaf or petiole used by climbing plants to hold and climb onto objects or onto other plants for support.^[1]

Many plants have tendrils. For example, sweet peas, passionflower, grapes and the Chilean glory-flower. When tendrils feel touch or chemicals, they curl, twine or stick to objects for support.

The first and most detailed study of tendrils was made by Charles Darwin on a monograph which was published in the year 1865.

The study was about the Movements and Habits of Climbing Plants. The study used a new term "circumnutation" for describing the motion of growing stems and tendrils looking for support.

Darwin also observed the rolling of tendrils into a coil shape, then rotating and coiling in the opposite direction. This phenomenon is now known as tendril perversion.^[2]

Only the terminal leaflets transform into tendrils in garden peas. In other plants like the yellow vetch, the whole leaf transforms into a tendril. The stipules of the plant become larger to support photosynthesis without leaves.^[3]

Plants of the genus Clematis use the rachis of the compound leaves as a tendril.

The specialised pitcher traps of plants of genus Nepenthes form on the end of tendrils. The tendrils of pitcher traps that are suspended in air usually coil in the middle. If the tendril comes into contact with an object for a long time, then it will curl around that object. This creates a strong anchor point for the pitcher trap. Tendrils help to support the growing stem of the plant this way.

Tendrils of the parasitic plant Cuscuta move toward the chemicals in air and only twine around suitable hosts.

Plants usually climb up to the canopy to receive more sunlight. This helps increase diversification of flowering plants.^[4] Diversification of flowering plants shortly means the formation of many different species from earlier ancestor species.

Tendrils are plant organs that develop from plant structures. For example, stems, leaves and inflorescences (flower clusters). Climbing habits are also present in angiosperms, gymnosperms, and ferns^[5] but the tendrils used for climbing are mostly found in angiosperms and less in ferns.

Tendrils coil in similar ways even if they develop from different plant structures.^[6] Scientists have found 17 types of tendrils based on which plant structure they develop from and how they grow. The same type of tendril may have evolved independently in different angiosperms. For example, the tendrils of watermelon plants develop from stems, pea tendrils develop from terminal leaflets, and common grapevine tendrils develop from flower clusters.^[7]

Parasitic plants like Cuscuta use tendrils for cellular invasion.^[1]

The length of tendrils is different in every plant. In Nepenthes Harryana, the length of tendrils range from a few centimetres up to 69 centimetres (27 inches).^[8]

Tendrils in Tetrastigma voinieranum, also known as chestnut vine, can grow up to 52 centimetres in length.

Plants normally only have one simple or branched tendril at each node, but the aardvark cucumber can have up to eight simple or branched tendrils.^[9]