Re: How do vines and similar plants find something to climb?

Vines climb using several techniques, twining stems, tendrils (modified stems or leaves that wrap around a support) and clinging adventitious roots on stems. Vines that twine or have tendrils seem to respond to touch so if the stem or tendril touchs an object, it wraps around it, a response known as thigmotropism. A tropism is a directional growth response to a directional stimulus. In thigmotropism, contact with a solid object is the directional stimulus which causes the stem or tendril to wrap around the solid object. Growth oftens seems random so a vine may or may not encounter an object to climb.

Stems of some vines, such as English ivy, also are negatively phototropic, meaning they grow away from a light source. This increases their chances of encountering a tree trunk or wall to climb on. I have seen an English ivy stem exhibiting negative phototropism by growing into a dark basement through a crack in a foundation. Non climbing plants usually have positively phototropic stems.