A trellis is any structure built or erected to support climbing plants and vines. Many formal trellis designs exist, usually in the form of a gridwork of wood or metal. The word is sometimes used as a verb, as in, “trellis this climbing cucumber variety for the straightest fruits.” Plants can be trellised over fences, up walls, even up trees if there is enough light. One grower here in Delta trellises his pumpkins up sturdy ladders in a way that allows the fruits to hang down beneath the bulky plants.
Trellising allows plants to grow towards the light, and at the same time, their fruits can hang down and grow straight, rather than curling up on the ground.