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Xerophiles are "xerotolerant", meaning tolerant of dry conditions. They can often survive in environments with water activity below 0.8; above which is typical for most life on Earth. Typically xerotolerance is used with respect to matrix drying, where a substance has a low water concentration. These environments include arid desert soils.
Many plants and seeds recognize this and enter a dormant period in the fall to stop growing. The grain is a popular example in this aspect, where they would die above ground during the winter, so dormancy is favorable to its seedlings but extensive domestication and crossbreeding has removed most dormancy mechanisms that their ancestors had.
Most of these plants are small, roundish, dense shrubs represented by species of Papilionaceae, some inconspicuous Compositae, a few Zygophyllaceae and some grasses. Water is stored in the bulbs of some plants, or at below ground level. They may be dormant during drought conditions and are, therefore, known as drought evaders.
Annual plants in deserts may use the weedy ephemeral strategy to survive in the desert environment. These species survive the dry seasons through seed dormancy. Alternatively, some perennial desert plants may die back to their underground parts and become dormant when there is not enough water available. [3]
Bacteria genera found in both air samples and the Antarctic include Staphylococcus, Bacillus, Corynebacterium, Micrococcus, Streptococcus, Neisseria, and Pseudomonas. [7] Bacteria were also found living in the cold and dark in a lake buried a half-mile deep (0.80 km) under the ice in Antarctica. [10] [11] [12]
A microbial mat is a multi-layered sheet or biofilm of microbial colonies, composed of mainly bacteria and/or archaea. Microbial mats grow at interfaces between different types of material, mostly on submerged or moist surfaces, but a few survive in deserts. [1] A few are found as endosymbionts of animals.
In most such species, the tumbleweed is in effect the entire plant apart from the root system, but in other plants, a hollow fruit or inflorescence might detach instead. [1] Xerophyte tumbleweed species occur most commonly in steppe and arid ecosystems , where frequent wind and the open environment permit rolling without prohibitive obstruction.
Selaginella lepidophylla, the seemingly fragile resurrection plant, forms a crucial partnership with desert soil bacteria. [10] During its dormant state, S. lepidophylla releases organic compounds that stimulate the growth of beneficial bacteria, creating a protective layer around its roots. In turn, these bacteria aid in nutrient acquisition ...