How are trees able to transport water from their roots to their tops?

Given that large broadleaf trees lose a lot of water on hot days, and some Redwoods can reach heights of more than 300 ft, it is obvious that enormous amounts of water must be moved. I don't think capillary action can account for this, and at the risk of sounding stupid, trees don't have hearts. Informed responses are appreciated.

How are trees able to transport water from their roots to their tops?
It is combination of things. Capillary movement is a very small part of it and one of the reasons that it is possible. Tension and cohesion of water is yet another that makes it possible. However, what makes it all work is the process of transpiration. Transpiration is the evaporation of water from the leaf surface through the stoma. This evaporation causes the water to be pulled through the plant.





Capillary movement only moves the water very short distances. Within the xylem there are plates called sieve plates, these prevent air bubbles that would break the cohesion.





This is a very simple explanation and leaves out other factors that are very important. For more information run a search on yahoo or Google with transpiration or water movement in plants and read through those.
Reply:By capillary action in the bark of the tree
Reply:Capillary action alone is too weak and air pressure can only push up to 30m or so I think. 2nd answer up there is probably right. As water molecules leave by evaporating it pulls other water molecules slightly up through weak force (hydrogen bond, its same force that can make water droplets stick to glass). From what I remember I it was combination of capillary and weak force among water molecules (may some osmotic pressure in there too).
Reply:capillary action, yes, but it might be assisted by wind blowing over the surface of the entire tree/leaves and causing a low pressure zone, so that it aids in the assent of the fluids along with heat/thermal fluidic transience.
Reply:The xylem transports sap from the root up the plant: xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well.





This transport is not powered by energy spent by the tracheary elements themselves, which are dead at maturity and no longer have living contents. Two phenomena cause xylem sap to flow:





The soil solution (see soil) is more dilute than the cytosol of the root cells. Thus, water moves osmotically into the cells, creating root pressure. Root pressure is very variable between different plants.


By far the most important cause of xylem sap flow is transpirational pull. The reverse of root pressure, this is caused by the transpiration of water. In larger plants such as trees, the root pressure and transpirational pull work together as a pump that pull.








Plants by the way develop ways to adapted to there environment. for example the plants that u said have large leaves. the pattern of the leaves could be overlapping so that not all leaves are exposed.Such plants have some xeromorphic features in order that they should conserve enough water such as a cuticle, stomata with regulable diameter, and a greater number of stomata on the undersides of leaves.Again they have no specific adaptations to overcome this, and can only respond by closing their stomata to prevent further dehydration. Their cells are thus likely to lose turgidity. This may cause the plants cells to become plasmolysed. prompting wilting. Wilting does actually have some benefits as it reduces the leaf surface area exposed to the atmosphere, meaning it reduces transpiration, and that exposed to solar radiation, meaning temperature stress is reduced. Although mesophytes often recover from such wilting, prolonged periods of it can lead to permanent wilting or cell plasmolysis and subsequently death.


-----sorry for the long sorry. but u do understand now right?------------------
Reply:capillarity of the xylem, and the sucking power of the leaves. The pressure in the root support the water cames up too.
Reply:You already know the answer. Its called transparation. The evaporation of the moisture through the leaves enhances the capillary action, drawing water through the roots and then either the xylem or ploem( i forget which). I also think it has something yo do with cellular density, as the cells higher in the plant lose water the cells equalize pressure by moving more water vertically.
Reply:Never underestimate the forces of turgor pressure.You are dealing with a living organism which depends on its' existence of a whole lattice-work of engineering and chemical pathways..phloem and xylem etc etc .Sorry ,the lady before has said most of what you want to know.
Reply:yes it is capillary action.