Xerophyte - wikipedia Xerophyte This article has multiple issues. Please help improve it or discuss these issues on the talk page. ( Learn how and when to remove these template messages ) This article needs attention from an expert in plants. Please add a reason or a talk parameter to this template to explain the issue with the article. WikiProject Plants may be able to help recruit an expert. ( June 2011 ) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( June 2011 ) The Joshua tree is an example of a xerophyte. A xerophyte ( from Greek ξηρός xeros dry, φυτόν phuton plant ) is a species of plant that has adaptations to survive in an environment with little liquid water, such as a desert or an ice - or snow - covered region in the Alps or the Arctic. The morphology and physiology of xerophytes are variously adapted to conserve water, and commonly also to store large quantities of water, during dry periods. Other species may be able to survive long periods of desiccation of their tissues, during which their metabolic activity may effectively shut down. Plants with such morphological and physiological adaptations are xeromorphic. Contents 1 Introduction 2 Types of xerophytes 3 Importance of water conservation 4 Morphological adaptations 4.1 Reduction of surface area 4.2 Reduction in air flow 4.3 Reflectivity 5 Physiological adaptations 6 Modification of environment 7 Mechanism table 8 See also 9 References 10 Further reading 11 External links Introduction Plants absorb water from the soil, which then evaporates from their outer surfaces ; this process is known as transpiration. In dry environments, a typical ( mesophytic ) plant would evaporate water faster than the rate at which water was replaced in the soil, leading to wilting. To reduce this effect, xerophytic plants exhibit a variety of specialized adaptations to survive in such conditions. Xerophytes may use water from their own storage, allocate water specifically to sites of new tissue growth, or lose less water to the atmosphere and so convert a greater proportion of water in the soil to growth, or have other adaptations to manage water supply and enable them to survive. Cacti and other succulents are commonly found in deserts, where there is little rainfall. Other xerophytes, such as certain bromeliads, can survive through both extremely wet and extremely dry periods and can be found in seasonally moist habitats such as tropical forests, exploiting niches where water supplies are too intermittent for mesophytic plants to survive. Likewise, chaparral plants are adapted to Mediterranean climates, which have wet winters and dry summers. Plants that live under arctic conditions also have a need for xerophytic adaptations, since water is unavailable for uptake when the ground is frozen. Types of xerophytes This section needs expansion. You can help by adding to it. ( June 2011 ) Succulent plants store water in their stems or leaves. They include the Cactaceae family, which has round stems and can store a lot of water. The leaves are often vestigial, as in the case of cacti, wherein the leaves are reduced to spines, or they do not have leaves at all. Non-succulent Perennials, another type of xerophytes, successfully endure long and continuous dearth of water in the soil. These are hence called ' true xerophytes ' or euxerophytes. Water deficiency usually reaches 60 -- 70 % of their fresh weight, as a result of which the growth process of the whole plant is hindered during cell elongation. The plants which survive drought are, understandably, small and weak. Ephemerals are the ' drought escaping ' kind, and not true xerophytes. They do not really endure drought, only escape it. With the onset of rains, the plant seeds germinate, quickly grow to maturity, flower and set seed, i.e., the entire life cycle is completed before the soil dries out again. Most of these plants are small, roundish, dense shrubs represented by species of Papilionaceae, some inconspicuous Compositae, a few Zygophyllaceae and some grasses. Xerophytes are commonly found in arid environments, where plants such as pineapples and cacti may grow. Water is stored in the bulbs of some plants, at or below ground level. They may be dormant during drought conditions and are, therefore, known as drought evaders. Importance of water conservation If the water potential ( or strictly, water vapour potential ) inside a leaf is higher than outside, the water vapour will diffuse out of the leaf down this gradient. This loss of water vapour from the leaves is called transpiration, and the water vapour diffuses through the open stomata. Transpiration is natural and inevitable for plants, and much water is lost through this process. However, it is vital that plants living in dry conditions are adapted so as to reduce this water loss and decrease the size of the open stomata, in order to reduce unnecessary loss from the plant. It is important for a plant living in these conditions to conserve water because, without enough water, plant cells lose turgor. This is known as plasmolysis. If the plant loses too much water, it will pass its permanent wilting point, and die. In brief, the rate of transpiration is governed by the number of stomata, leaf area ( allowing for more stomata ), temperature differential, the relative humidity, the presence of wind or air movement, the light intensity, and the presence of a waxy cuticle. It is important to note, that whilst it is vital to keep stomata closed, they have to be opened for gaseous exchange in photosynthesis. Morphological adaptations Cereus peruvianus Euphorbia virosa The cactus Cereus peruvianus looks superficially very similar to Euphorbia virosa due to convergent evolution. Xerophytic plants may have similar shapes, forms, and structures and look very similar, even if the plants are not very closely related, through a process called convergent evolution. For example, some species of cacti ( members of the family Cactaceae ), which evolved only in the Americas, may appear similar to Euphorbia s, which are distributed worldwide. An unrelated species of caudiciforms, plants with swollen bases that are used to store water, may also display such similarities. Reduction of surface area Xerophytic plants can have less overall surface area than other plants, so reducing the area that is exposed to the air and reducing water loss by evaporation. Xerophytes can have smaller leaves or fewer branches than other plants. An example of leaf surface reduction are the spines of a cactus. An example of compaction and reduction of branching are the barrel cacti. Other xerophytes may have their leaves compacted at the base, as in a basal rosette, which may be smaller than the plant 's flower. This adaptation is exhibited by some Agave and Eriogonum species, which can be found growing near Death Valley. Reduction in air flow Some xerophytes have tiny hairs on their surface to provide a wind break and reduce air flow, thereby reducing the rate of evaporation. When a plant surface is covered with tiny hairs, it is called tomentose. In a still environment, the areas under the leaves / spines where transpiration is taking place form a small localised environment that is more saturated than normal with water vapour. If this is not blown away by wind, the water vapour potential gradient is reduced and so is transpiration. Thus, in a windier situation, this localization is not held and so the gradient remains high, which aids the loss of water vapour. Spines trap a layer of moisture and also slow air movement over tissues. Reflectivity The color of a plant, or of the waxes or hairs on its surface, may serve to reflect sunlight and reduce evaporation. An example is the white chalky wax ( epicuticular wax ) coating of Dudleya brittonii, which has the highest ultraviolet light ( UV ) reflectivity of any known naturally occurring biological substance. Physiological adaptations Some plants can store water in root structures, trunk structures, stems, and leaves. Water storage in swollen parts of the plant is known as succulence. A swollen trunk or root at the ground level of a plant is called a caudex and plants with swollen bases are called caudiciforms. The stomata may open only at night, so as to reduce evaporation. Plants may secrete resins and waxes ( epicuticular wax ) on their surfaces, which reduce evaporation. Examples are the heavily scented and flammable resins ( volatile organic compounds ) of some chaparral plants, such as Malosma laurina, or the chalky wax of Dudleya pulverulenta. Plants may drop their leaves in times of dryness ( drought deciduous ), or modify the leaves produced so that they are smaller. During dry times, xerophytic plants may stop growing and go dormant, or change the allocation of the products of photosynthesis from growing new leaves to the roots. Seeds may be modified to require an excessive amount of water before germinating, so as to ensure a sufficient water supply for the seedling 's survival. An example of this is the California poppy, whose seeds lie dormant during drought and then germinate, grow, flower, and form seeds within four weeks of rainfall. Modification of environment The leaf litter on the ground around a plant can provide an evaporative barrier to prevent water loss. A plant 's root mass itself may also hold organic material that retains water, as in the case of the arrowweed ( Pluchea sericea ). Mechanism table Mechanism Adaptation Example Limit water loss waxy stomata prickly pear few stomata sunken stomata pine stomata open at night tea plant CAM photosynthesis cactus large hairs on surface Bromeliads curled leaves esparto grass Storage of water succulent leaves Kalanchoe succulent stems Euphorbia fleshy tuber Raphionacme Water uptake deep root system Acacia, Prosopis below water table Nerium oleander absorbing surface moisture from leaf hairs or trichomes Tillandsia See also Index : Desert flora Arid Forest Research Institute ( AFRI ) Halophyte Hydrophyte International Center for Agricultural Research in the Dry Areas International Crops Research Institute for the Semi-Arid Tropics Kinetic Theory Raunkiær plant life - form Xeriscaping Xerocole References Jump up ^ '' Xeromorphic '', The Cambridge Illustrated Glossary of Botanical Terms, Michael Hickey, Clive King, Cambridge University Press, 2001 Jump up ^ Mulroy, Thomas W. ( 1979 ). `` Spectral properties of heavily glaucous and non-glaucous leaves of a succulent rosette - plant ''. Oecologia. 38 ( 3 ) : 349 -- 357. doi : 10.1007 / BF00345193. Jump up ^ `` Plant Adaptations ''. University of New Mexico. Archived from the original on January 4, 2015. Retrieved December 2, 2014. Further reading D.J. Taylor ; N.P.O. Green ; G.W. Stout ( 2001 ). Biological Science 1 & 2 ( Third ed. ). Cambridge University Press. ISBN 0 - 521 - 56178 - 7. External links Wikimedia Commons has media related to Xerophytes. Drought Smart Plants Cactus and Succulent Society of America Retrieved from `` https://en.wikipedia.org/w/index.php?title=Xerophyte&oldid=826111656 '' Categories : Drought - tolerant plants Plant morphology Deserts and xeric shrublands Desert flora Drought - tolerant trees Xerophiles Hidden categories : Articles needing expert attention with no reason or talk parameter Articles needing expert attention from June 2011 All articles needing expert attention Plants articles needing expert attention Articles needing additional references from June 2011 All articles needing additional references Articles with multiple maintenance issues Articles to be expanded from June 2011 All articles to be expanded Articles using small message boxes All articles with unsourced statements Articles with unsourced statements from April 2017 Articles with unsourced statements from April 2011 Talk Contents About Wikipedia Afrikaans Беларуская Български Bosanski Català Čeština Dansk Deutsch Eesti Ελληνικά Esperanto Euskara فارسی Français 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Italiano Қазақша Кыргызча Lietuvių Bahasa Melayu Nederlands Norsk Norsk nynorsk Oʻzbekcha / ўзбекча Polski Português Română Русский Simple English Slovenščina Srpskohrvatski / српскохрватски Suomi Svenska తెలుగు ᏣᎳᎩ Türkçe Українська Edit links This page was last edited on 17 February 2018, at 07 : 14. 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Question: type of plant adapted to reduce water loss
Answer: xerophytes