Climbing plants

Climbing plants make up a large, unrelated group of plants that are adapted in various ways for climbing up supports or other plants to reach the light. Some plants, such as cleavers or goosegrass, have curved outgrowths that point downwards and serve as a means of scrambling up other vegetation. Ivy stems bear roots which give out a sticky fluid and glue the plant to its support. Many plants have thread-like outgrowths called tendrils, which are usually modifications of leaves or parts of leaves.
The tendrils twine around anything they touch, giving the plant support. The reduction in leaf area due to tendrils in leguminous plants such as vetches and sweet peas is balanced by the development of leafy outgrowths called stipules at the base of the leaf stalk. Hence, the food-making capacity of the plant is not reduced.

A third group of climbers achieve their aim by winding their stems round the stems of other plants. Convolvulus and honeysuckle are two common examples of twining plants, but there is a major difference between them: convolvulus twines in an anticlockwise direction (looked at from above the plant), whereas honeysuckle twines clockwise. Twining plants commonly bear only tiny leaves near the top of the stem, and these are separated from each other by long sections of stem. Such an arrangement means that the stem can twine around the support before the leaves become large enough to interfere. Twining plants are particularly common in tropical rain forests where they are generally called lianas.

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