The present explanation for water transport in plants, tall trees (coconut, red woods etc) centers around osmosis, transpiration pull, adhesion and cohesion forces of water molecules in xylem vessels and tracheids.  Tall coconut trees are around 98 feet, but California redwoods are 360 feet tall.

"Passive, hydraulic redistribution of water from moister to drier portions of the soil profile via plant root systems may have a substantial impact on vertical profiles of soil water distribution, partitioning of water within and among species, and on ecosystem water balance. The recent development of a technique for direct measurement of pressure in individual xylem elements of intact, transpiring plants elicited a number of challenges to the century-old cohesion–tension theory. The ongoing debate over mechanisms of long-distance water transport has stimulated an intense interest in the phenomenon and mechanisms of embolism repair. Rather than embolism being essentially irreversible, it now appears that there is a

dynamic balance between embolism formation and repair throughout the day and that daily release of water from the xylem via cavitation may serve to stabilize leaf water balance by minimizing the temporal imbalance between water supply and demand"...

http://www.fs.fed.us/pnw/pubs/journals/meinzer-watertransport.pdf

@Miranda Yeoh  thank you for your valuable reply.. I was looking to a simpler explanation of the phenomena  with an idea if a coconut tree trunk  immersed in a well could be used to draw up the water without external energy input.. your suggestions on this would be greatly appreciated ..thank you once again..

Cheers

Miranda is correct. Water transport in trees is driven by evaporation from the leaves which produces tension in the water column pulling the water up from the roots.  If you are asking whether you could drop a palm tree into a well, cut off the top and have it pump water for you the answer is no I'm sorry to say.  It is a passive system.  There is no active pump in the stem. 

Philip Lintilhac  Thank you for a valuable insight.. yes that was sort of (is?) my pipe dream.

Capillary action lifts liquiid based on surface tension..A long time ago Parker had a self- filling pen based on this. Heat pipes can take heat down and steam up water..Even in the coconut tree I imagine a depression in the ground and the tree reaching ground level.with some tapping mechanism at the nut nodes so we can extract water ..But there seems something quite mysterious in transport of water over such a long distance , my thinking is apart from physics and chemistry there may be a biological basis..It would be interesting to know a simplified (sketch ) which explains this (if at all there) to a non- biolgist..Thanks once again for your patience..

Cheers

Some interesting ,I think, connected news  :

quote"

World's smallest engine developed

London, May 3, 2016, (PTI):

Scientists have developed the world's tiniest engine - just a few billionths of a metre in size - which is powered by light and may help develop nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease.

The prototype device is made of tiny charged particles of gold, bound together with temperature-responsive polymers in the form of a gel.

When the 'nano-engine' is heated to a certain temperature with a laser, it stores large amounts of elastic energy in a fraction of a second, as the polymer coatings expel all the water from the gel and collapse.

This has the effect of forcing the gold nanoparticles to bind together into tight clusters.

When the device is cooled, the polymers take on water and expand, and the gold nanoparticles are strongly and quickly pushed apart, like a spring.

"It's like an explosion. We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them," said Tao Ding from University of Cambridge in the UK.

"We know that light can heat up water to power steam engines. But now we can use light to power a piston engine at the nanoscale," said Ventsislav Valev, now based at the University of Bath.

Nano-machines have long been a dream of scientists and public alike, but since ways to actually make them move have yet to be developed, they have remained in the realm of science fiction.

The new method is simple, and can be extremely fast and exert large forces, researchers said.

The forces exerted by these tiny devices are several orders of magnitude larger than those for any other previously produced device, with a force per unit weight nearly a hundred times better than any motor or muscle.

According to the researchers, the devices are also bio-compatible, cost-effective to manufacture, fast to respond, and energy efficient.

Jeremy Baumberg from the University of Cambridge, who led the research, has named the devices 'ANTs', or actuating nano-transducers.

"Like real ants, they produce large forces for their weight. The challenge we now face is how to control that force for nano-machinery applications," Baumberg said.

The research suggests how to turn Van der Waals energy - the attraction between atoms and molecules - into elastic energy of polymers and release it very quickly.

"The smart part here is we make use of Van der Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible," said Baumberg.

The research was published in the journal PNAS.  "unquote

Cheers

Coconut is a herb but there are real trees that can reach 100m of prevalence by using osmotic pumps in the leaves and transpiration pull, the same principle that dries a wet cloth under sun. Getting high is an advantage for catching the sun, but the great plus for difffusion was salt tolererance and seed buoyancy, as in a nice teacher note https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwj8jILwusLMAhUH2hoKHWzvCycQFggoMAE&url=http%3A%2F%2Fwww.saps.org.uk%2Fattachments%2Farticle%2F840%2FSAPS-%2520The%2520physics%2520of%2520coconuts%2520-%2520teacher%2520notes.doc&usg=AFQjCNGWgQ91zTUuOfe_aWJTUHdXGt0e3Q&sig2=-CzSbplQQiD-G3Fqo948YA&cad=rja

    Guido Bongi Thank you very much for a nice report on the coconut tree.I found some sites,  in line with  your comment (which were appealing to me) below . It would seem small gia  nano tubes in bundles with a heat collector at top (also to collect evaporated water ) could be visualized as a simple pump engineering wise.

http://www.scientificamerican.com/article/how-do-large-trees-such-a/

http://www.biology-pages.info/X/Xylem.html

Cheers

You are welcome and thanks for refs. That is how but let us forget about the tree. Cocos are not a tree but a palm. The vessels bundles we are talking about are 100 micron wide but the wood thickens near the cork and is soft in the center of the stem, opposite of what happens in trees. The water goes up to fronds by transpiration but part of it enters the green cells thanks to internal osmotic pumps. All this in a saline environment around the roots.