Deserts

Only a few plants can live and develop and desert conditions, but these few have adapted so much to the climate there that nothing else will suit them. Even the metabolism of most desert dwellers is built quite differently than that of all the other representatives of the vegetable kingdom, so that they are not even "retrained" by acclimatization. In ordinary plants, photosynthesis occurs in the daytime, in many succulents, on the contrary, carbon dioxide is absorbed only at night, and in the daytime the stomata are closed to prevent evaporation of moisture from the body.

Deserts( I apologize for the tautology) therefore the desert, which is empty in them. Relatively, of course. The brightest and most characteristic sign of the desert is low humidity. In natural conditions, there falls less than 20 cm of precipitation a year, and sometimes less: in the Atacama Desert( the coast of Peru and northern Chile), their average annual number rarely exceeds 1 cm! For comparison: in a moderate climate, they range from 75 to 250 cm, in the humid tropics - from 200 to 400 cm, in rain rainforests, even more: up to 2000 cm per year. Consequently, compared with some other indoor plants, descendants of the desert sometimes need two hundred times less moisture. In addition to the required total amount of water, the need to remember the peculiarity of the regime of its supply: in deserts, precipitation falls unevenly over the seasons, and therefore for herbaceous species there is a sharp seasonal change in vegetative activity( that is, there are one or two periods of intensive growth and, accordingly, periods of deep dormancy).

Most deserts are characterized by very high temperatures. In the African deserts, they usually exceed 36 ° C in the summer, the deserts of North America are colder. Water vapor in the air of deserts can not condense properly, so that the atmospheric humidity there is very small.

There are no trees in the deserts that give a shadow, and therefore the plants permanently living there have adapted to direct sunlight: they have leaves or are absent( cactuses), or leathery, with a small number of stomata, covered with a special wax or fat protective layer - cuticle.

So: desert plants are drought-resistant, thermophilic, but are accustomed to sharp daily fluctuations in temperature, are light-loving, do not fear sunburn, bulbous desert species require a long period of rest.