Thorns are sharp, pointed structures that are actually modified stems, leaves, or roots. They are found on many different types of plants and serve several functions:

* Defense: Thorns protect plants from herbivores (animals that eat plants). The sharp points deter animals from eating the plant.

* Support: Some thorns can help support climbing plants.

* Water retention: Thorns can help reduce water loss in dry environments.

Other structures that might look like horns on plants:

* Spines: These are sharp, pointed structures that are actually modified leaves. Like thorns, they protect the plant from herbivores.

* Prickles: These are outgrowths of the plant's epidermis (outer layer) and are not as strongly attached to the plant as thorns or spines. They are also used for defense.

To give you a more specific answer, I need more information about the plant in question. Could you describe the plant, or tell me where you saw it? For example:

* What kind of plant is it? (tree, shrub, vine, etc.)

* Where did you see it? (forest, desert, garden, etc.)

* What do the structures look like? (size, shape, color, etc.)

Once I have more information, I can help you identify the structures and their purpose!