Of the thorns or spines and the greeny pigmented hard part of the cactus are the leaves and why?​

The spines of a cactus are exactly not the leaves, but they are the solid hard part that reduces the rate of transpiration, so as to level the water constant in the cactus' body. They are important as it can reduce the animals from eating the cactus.

However, camels have thick jaws and can eat cactus easily .

Hope it helps you...

(Answered by Benjemin)

plant because they survive by water, sunlight, ex.

explanation:

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]