tendril

A tendril is a slender, threadlike plant structure that enables climbing by attaching to and supporting the plant as it grows. Tendrils are specialized organs that can originate from different parts of the plant, most commonly from leaves or leaflets, but also from stems or inflorescences. In many vines a leaf blade is modified into a tendril, while in others a slender branch or a pair of leaflets becomes a tendril.

Tendrils respond to contact and aid in anchoring the plant to supports. When a tendril encounters a solid surface, it often coils around it, a process driven by thigmotropism and circumnutation. The curling results from differential growth and turgor changes along the tendril, allowing it to wrap tightly around a pole, wire, or other structure. Some tendrils terminate in adhesive pads that can attach to smooth surfaces, as seen in certain species such as Virginia creeper, while others simply coil without pads.

The climbing habit facilitated by tendrils reduces the need for a thick, sturdy main stem and helps plants reach light, particularly in dense vegetation. Tendrils occur in several plant families, including Vitaceae (grapes), Fabaceae (peas and related climbing legumes), Cucurbitaceae (cucumbers and melons), and Passifloraceae (passionflowers). Tendrils may be simple or branched and can be modified from leaves, leaflets, stems, or inflorescences, reflecting diverse evolutionary origins. Examples include Vitis vinifera (grape), Pisum sativum (pea), Lathyrus odoratus (sweet pea), Cucumis sativus (cucumber), and Passiflora species.