X

X is for Xerophyte...  or xerophytic organism (xero meaning dry, phyte meaning plant) is an organism, which is able to survive in an ecosystem with little to no water or moisture.
Wikipedia says:

"Xerophytic plants can survive in areas in which a typical (mesophytic) plant would take up water from the soil and evaporate it faster than the rate at which water is replaced in the soil, such as by rainfall, leading to the subsequent wilting of the typical mesophytic plant. Taking up water from the soil and evaporating it is called evapotranspiration. As contrasted with mesophytic plants, xerophytic plants may absorb water from their own storage, change their allocation of water to where new tissues are grown, lose less water to the atmosphere and so convert a greater proportion of water in the soil to growth, or have other adaptations to enable them to survive.
Plants like the cactus (plural - "cacti", family - Cactaceae) and other succulents are typically found in deserts where low rainfall amounts are the norm. But xerophytes, such as the bromeliads that can survive both expremely wet and extremely dry peroids, can also be found in seasonally moist habitats such as tropical forests, exploiting niches where water supplies are limited or too intermittent for mesophytic plants. Similarly, chaparral plants are adapted to Mediterranean climates with wet winters and dry summers. Plants that live under arctic conditions have a need for xerophytic adaptations, since water is unavailable for uptake when the ground is frozen. Plants that survive lack of water during times of freezing by going dormant with no other adaptations for times of low water are not usually referred to as xerophytic.^{[citation needed]}
Xerophytic plants may have surface areas covered with fine hairs which create a wind break reducing water being carried away by wind, have a light colored surface or surface coating which relects light and the reduced heating reduces evaporation, have water stored in swollen tissues, or have compacted forms so there is less surface area which reduces the amount of evaporation in proportion to the plant's mass. Adaptations of xerophytes include reducing the amount of water that may leave the plant's "skin", i.e., reduced permeability of the epidermal layer, closing of the plant's "pores" (stomata) during the hot day, and opening during the cool night. The plant's cuticle may be adapted to maintain an optimal amount of water in the tissues by reducing transpiration. Adaptations of the root system to acquire water from deep underground sources or directly from humid atmospheres (as in epiphytic orchids), and succulence, or storage of water in swollen stems, leaves or root tissues. The typical morphological consequences of these adaptations are collectively called xeromorphisms. ^[1]"