tendril

tendril, slender, sensitive structure of many climbing plants that by a response to contact (see auxin) supports the plant. Tendrils are modified stems, leaves, or leaf parts or roots. Most young tendrils revolve slowly in their natural growth, as do the growing tips of roots and shoots; the tendrils of different plant varieties may have a consistent tendency to clockwise or to counterclockwise spiraling. The most common kind of tendril (pea, grape) coils around a slender support and then contracts spirally, becoming springy and drawing the plant to the support. The disk-tipped tendril (Virginia creeper, Boston ivy) adheres firmly to brick, stone, or wood, after which it too contracts. For other means of climbing in plants, see climbing plant.

Plant organ specialized to anchor and support vining stems. A tendril is a slender, whiplike or threadlike strand, produced usually from the node of a stem and composed of either stem or leafstalk tissue, by which a vine or other plant may climb. Sensitive to contact, the tendril turns toward any object it brushes against, wraps about it, and clings to it for as long as the stimulation persists. Later, strong mechanical tissue develops in the tendrils, making them strong enough to support the weight of the plant. Some tendrils have enlargements at the ends that flatten and produce an adhesive that firmly cements them to their support. Common examples of tendril plants are grape, English ivy, sweet pea, gourds, and passionflowers.

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In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support and attachment, generally by twining around whatever it touches.

History

The earliest and most comprehensive study of tendrils was Charles Darwin's monograph On the Movements and Habits of Climbing Plants, which was originally published in 1865. This work also coined the term circumnutation to describe the motion of growing stems and tendrils seeking supports.

Biology of tendrils

In the garden pea, it is only the terminal leaflets that are modified to become tendrils. In other plants such as the yellow vetch (Lathyrus aphaca) the whole leaf is modified to become tendrils while the stipules become enlarged and carry out photosynthesis. Still others use the rachis of a compound leaf as a tendril, such as members of the genus Clematis.

The specialised pitcher traps of Nepenthes plants form on the end of tendrils. The tendrils of aerial pitchers are usually coiled in the middle. If the tendril comes into contact with an object for long enough it will usually curl around it, forming a strong anchor point for the pitcher. In this way, the tendrils help to support the growing stem of the plant.

Tendril can also be used to describe a wisp of hair or indeed anything that resembles the tendrils of plants.

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