Bio%20201%20S12%20Lect%2013%20%28True%29%20v3

A large tree will transpire 10s of 1000s of gallons

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Unformatted text preview: ater storage •  other plants – no special structures – complete enEre life cycle during brief wet periods structural adaptaEons for dry climates = “xerophyEc” adaptaEons •  thick epidermis •  dense, hairy covering •  stomatal crypts –  recessed stomata •  eucalytpus: leaves hang verEcally to avoid direct sunlight •  succulence •  spines –  photosynthesis is stems, not leaves –  may deflect solar radiaEon or funcEon in heat dissipaEon but there is a cost to being a xerophyte •  typically slow growth •  why? –  keeping stomates closed to reduce water loss also reduces CO2 intake –  also can only grow in brief Emes of the year adaptaEon of most xerophytes: higher water use efficiency than other plants root adaptaEons of desert plants •  very deep taproots or •  very fast growing roots acEve during brief wet seasons –  die back during dry seasons •  also: accumulaEon of proline in vacuoles –  creates more negaEve "solute potenEal" and "water potenEal" inside cells –  forces a greater rate of water intake by cells; more extracEon of water from environment •  plants in salt- rich environments also have this adaptaEon what about environments with too much water? •  •  •  hard for roots to get enough oxygen most plants cannot live long in flooded/ saturated soils some have adaptaEons –  slow root growth, very shallow soil penetraEon –  anaerobic metabolism (fermentaEon) instead of aerobic respiraEon in roots –  less efficient than aerobic respiraEon =>slow growth •  pneumatophores - extensions of roots that grow out of the water into air –  spongy Essue allows diffusion of oxygen for enEre root –  e.g. cypress, mangrove •  aerenchyma in leaves and peEoles –  have large air spaces for storage of Oxygen –  also increase buoyancy plants in hot environments •  transpiraEon can cool –  but also can dehydrate •  similar adaptaEons to some dry environments –  e.g. hairs and spines increase heat radiaEon •  expression of heat shock proteins –  help stabilize the folding of other proteins hNp://farm4.staEc.flickr.com/3208/3050617646_e92baf6f12.jpg?v=0 plants and cold •  low temps above freezing –  membranes lose fluidity –  Essue damage can occur •  freezing...
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This note was uploaded on 10/02/2013 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

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