What is the purpose of thorns in a rosebush?

Answer 1

The thorns of a cactus are a mutation or adaptation of what were once the leaves.

- The smaller surface area allows for less loss of water through evaporation.

- The pointy nature of the thorns works as a deterrent to animals that might otherwise chew through the outer layers for the water contained within the plant.
to prevent themselves being eaten by predators

Answer 2

Thorns serve two main purposes on a cactus plant. They defend and protect the cactus plant's stem and important body parts that are found on the stem. The stem is important, because it moves, processes and stores water and watery products and solutions. Important body parts are the breathing pores, or stomata, by which gases are exchanged between the plant's insides and the outside air. Other important body parts are the growth buds from which flowers, fruits, and seeds appear.

Thorns also direct any available moisture - be it dew, fog, or rain - to where it's most needed. They channel the moisture to the ground around the cactus. The moisture is taken in by the ground, to be added to the water table or, more importantly for the cactus, to be taken in by the roots.

Answer 3

The purpose of prickles, or rose thorns, is to protect the plant from predators.