How have cactus plants adapted to hot climates?

Cactus plants are adapted to the hot climates of the deserts of North and Latin America, and of the Latin American jungles. One way that they do so is through controlled breathing. Guard cells are stationed on both sides of the openings to stomata, or breathing pores. They control what gets in and out of the plant's stem.

Another way is through a flexible but thickened outer skin that also keeps inside what already is inside the cactus. Inside the stem are fleshy, juicy tissues that can hold 90% and more of the plant's weight in water and watery products and solutions. The inner and the outer skins cooperate in being flexible. They contract with lesser amounts of stored contents, and expand with more.

Still another way is through reduced leaf surfaces that minimize water loss through evaporation. The leaves are modified into narrower, thinner thorns, spines, spikes, quills, prongs, needles, hairs or bristles. They direct any available moisture down to the ground, to be added to soil moisture levels or taken in by the plant's roots.

Yet another way is through spreading, shallow, fibrous roots. The roots are close to the surface. They're aggressive in capturing moisture as soon as it breaks through the soil's surface. They anchor the plant, hold it in place, seek out moisture over a wide area, and support the soil food web.