# How Trees Lift Water

> A first study of coast redwoods in heat, reported in October 2026, found that photosynthesis in young trees’ needles roughly halved between 30 and 40 °C, and that in heat waves the trees close the pores on their needles. This film explains why that matters: how a tree lifts water a hundred metres with no pump. A suction pump stops at about ten metres; trees instead pull water up from the top, as evaporation from leaf pores tugs on unbroken threads of water held together by hydrogen bonds inside dead, hollow wood cells. We follow the idea from Dixon and Joly in 1895, see why the threads can snap into air bubbles, why redwoods may top out near 120 to 130 metres, and why fog and heat matter to the tallest trees on Earth. Raise a pump, open and close a leaf’s pores, pull a water thread until it breaks, and grow a tree to its limit.

Interactive film: https://www.planetpast.com/stories/how-trees-lift-water/  
Publisher: PlanetPast (https://www.planetpast.com/) · d => T('readPublished', l, { d: dateIn(d, l) }) 2026-10-19 · Biology, Physics, Earth science

## Prologue

### A hundred metres without a pump
*Trees in the news*

What heat does to the tallest trees.

The tallest tree known is a coast redwood a hundred and sixteen metres high. Every day it lifts water from the soil to its top needles, with no heart and no pump. How? That system is now in the news. In a study reported this autumn, scientists at UC Davis found that photosynthesis in young redwoods' needles, the way they make food from sunlight, roughly halved between thirty and forty degrees Celsius. In heat waves, the trees shut the tiny pores on their needles to save water, and that has a cost. To see why, start with a puzzle about pumps.

- **116.07 m**: Hyperion, a coast redwood (Guinness)

- at 30 °C: 100%
- at 40 °C: ≈ 50%

- **2**: heat waves measured in the forest
- **first**: study of how coast redwoods respond to heat

Prologue · The news

#### Redwoods in the heat

Science News (12 Oct 2026): L. Klinek, T. Magney and colleagues report in the Journal of Geophysical Research: Biogeosciences that photosynthesis in needles from younger coast redwoods roughly halved as temperature rose from 30 °C to 40 °C. Field sampling in Mendocino County, California, from July 2022 to October 2024 covered two heat waves; under extreme heat some needles were up to 10 °C warmer than the air, suggesting their stomata were at least partly closed. Troy Magney calls it the first study of how coast redwoods respond to heat.

A single first study on young trees; its authors say the threshold for lasting damage is still unknown. How to use: pick a chapter or press ← →; drag to rotate. Most steps have buttons.

The 3D scenes are schematic: sizes, speeds and molecules are not to scale.

Sources: [Science News: When climate change brings the heat, what happens to a mighty redwood? (12 Oct 2026)](https://www.sciencenews.org/article/climate-change-heat-redwood-temperature); [UC Davis: Coast redwoods slow their “breathing” and “eating” when temperatures spike (28 Sept 2026)](https://www.ucdavis.edu/climate/news/coast-redwoods-slow-their-breathing-and-eating-when-temperatures-spike); [Guinness World Records: Tallest tree living](https://www.guinnessworldrecords.com/world-records/tallest-tree-living)

## Chapter I · The puzzle

### No suction pump can do it
*Chapter I · The puzzle*

Why suction stops at about ten metres.

Try lifting water with a suction pump. Pumping takes the air out of the pipe, and the weight of the atmosphere, pressing on the water outside, pushes it up the pipe. But the air can only push so hard. Even with a perfect vacuum in the pipe, water stops rising at about ten point four metres. Above that, the pump just sucks on empty space. As the pipe keeps growing, the water stays put. A redwood lifts water more than ten times higher than this, with no pump at all. Something other than suction must be at work.

![A pump like this works only while the water lies within about 10 m of it. AI-generated still.](https://assets.planetpast.com/a/c8/c8e967bb84d3faea.jpg)

$$h_{\max} = \dfrac{p_{\text{air}}}{\rho\, g} \approx \dfrac{101\,000}{1000 \times 9.8} \approx 10.3\ \text{m}$$
- $p_{\text{air}}$: air pressure at sea level, pascals
- $\rho$: density of water
- $g$: gravity

Textbooks quote about 10.4 m; the exact figure depends on the day’s air pressure.

- best suction pump: ≈ 10.4 m
- Hyperion, tallest tree: 116.07 m

Chapter I · The puzzle

#### Pushed by the air

LibreTexts: even the best vacuum pump can pull water up to only about 10.4 m (34 ft), because the weight of a column that tall just balances the pressure of the atmosphere, about 0.1 MPa (one atmosphere). A “suction” pump does not really pull: it removes air, and the atmosphere pushes the water up.

Pipe and tank are drawn to scale with each other, not with a tree.

Sources: [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory); [Guinness World Records: Tallest tree living](https://www.guinnessworldrecords.com/world-records/tallest-tree-living)

## Chapter II · Pulled from the top

### Leaves that leak
*Chapter II · Pulled from the top*

Food in, water out.

The answer starts in the leaves. Their surfaces are dotted with tiny pores called stomata. They open to let in carbon dioxide, which the leaf needs to make sugar. But every open pore also lets water vapour out. Losing water this way is called transpiration, and it adds up. A large oak can give off about forty thousand gallons, some hundred and fifty thousand litres, of water in a year. Close the pores and the water stays in, but carbon dioxide cannot get in either. Every plant has to balance food against water, all day long.

![Each pore is framed by two guard cells that swell to open it and go slack to close it. AI-generated still.](https://assets.planetpast.com/a/55/550bccbefd8ad879.jpg)

![USGS: trees give off more water when it is hot, windy and dry, and less when the air is humid. AI-generated still.](https://assets.planetpast.com/a/b5/b53ae47658dbf2c6.jpg)

- **up to 90%**: of water taken up by roots may be lost by transpiration
- **≈ 10%**: of the moisture in the air comes from plants (USGS)

Chapter I · The puzzle

#### Transpiration

USGS: transpiration is the release of water vapour from plants, mostly through stomata on the leaves; it supplies about 10% of the moisture in the atmosphere. A large oak can transpire about 40,000 US gallons a year, an acre of corn 3,000–4,000 gallons a day, and the rate rises with temperature and wind and falls with humidity. Raven Biology (LibreTexts): up to 90% of the water a plant’s roots absorb may be lost this way.

40,000 US gallons is about 150,000 litres.

Sources: [USGS Water Science School: Evapotranspiration and the water cycle (PDF copy, Columbia IRI)](https://fdacourse.iri.columbia.edu/documents/M1U2_Clouds/Clouds_Readings/S3_Clouds_Readings/S3_Evapotranspiration_The_Water_Cycle_USGS.pdf); [LibreTexts Biology (Raven Biology): Movement of water and minerals in the xylem](https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map:_Raven_Biology_12th_Edition/36:_Transport_in_Plants/36.02:_Water_and_Mineral_Absorption/36.2.1:_Movement_of_Water_and_Minerals_in_the_Xylem)

### Water that holds together
*Chapter II · Pulled from the top*

A thread of molecules.

Water molecules are sticky. Each one forms weak links, called hydrogen bonds, with its neighbours, so water holds together as a continuous thread. That is cohesion. Water also clings to the walls of the narrow tubes it travels through. That is adhesion. Together they let a thin column of water behave a little like a rope. When a molecule evaporates from a leaf, it tugs the next one up behind it, and that one tugs the next, all the way down to the roots. Watch the thread move as the top evaporates.

![The same pull between molecules is what makes water bead into round drops. AI-generated still.](https://assets.planetpast.com/a/6f/6fec23f3c8b025f7.jpg)

- cohesion: water to water
- adhesion: water to the tube walls

- **≈ 200 ×**: the atmosphere’s push: the pull reported to break a column of water

Chapter II · Pulled from the top

#### Cohesion and adhesion

LibreTexts: cohesion is the property of water molecules to cling to each other through the hydrogen bonds they form; adhesion is the attraction of water to the walls of the xylem. Measurements suggest tensions as great as 21 MPa would be needed to break a column of water. Atmospheric pressure at sea level is about 0.1 MPa, so 21 MPa is about 200 times larger.

MPa: megapascal, a million pascals. Molecules drawn hugely enlarged; the bonds are shown as dashed lines.

Sources: [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory)

### Pulled, not pushed
*Chapter II · Pulled from the top*

Water under tension.

So the water in a tree is not pushed up from below. It is pulled from the top, and it is under tension, a pressure below zero, like a stretched rubber band. Botanists track it with a quantity called water potential, measured in megapascals; one megapascal is about ten times the push of the air. In one textbook example, it is about minus zero point two in the roots, minus zero point six in the stem, and minus one point five in a leaf at the top. Dry air is far lower still, around minus one hundred: not its pressure, but how hard it draws water in. Water always moves toward the lower value, so it flows from soil to root to leaf to sky, driven by the sun's energy, not the tree's.

- a pump pushes: pressure above zero
- a tree pulls: pressure below zero

- root: −0.2
- stem: −0.6
- leaf at the top: −1.5

- **the Sun**: supplies the energy that evaporates the water
- **≈ −2 MPa**: tension transpiration can create at the leaf surface (a separate measure)

- soil → root: −0.2
- root → stem → leaf: −0.6 → −1.5
- leaf → dry air: ≈ −100

Chapter II · Pulled from the top

#### Water potential

LibreTexts: transpiration creates a negative pressure (tension) of about −2 MPa at the leaf surface. In its example, water potential falls from about −0.2 MPa in root cells to −0.6 MPa in the stem, −1.5 MPa in a leaf at the tip of the tree and about −100 MPa in the atmosphere; water moves from higher to lower water potential.

Real values vary with species, time of day and how wet the soil is.

Sources: [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory)

### A branch in a bottle
*Chapter II · Pulled from the top*

The theory gets its first test.

This idea is called the cohesion-tension theory. Two Irish scientists, the botanist Henry Dixon and the physicist John Joly, published it in 1895. In one experiment, they sealed a leafy maple branch inside a thick glass tube, with its cut end reaching down into water. The branch kept drawing water up against three times normal air pressure. So the leaves pulled harder than three atmospheres could push back, far beyond what suction can do. They argued that the tree spends no effort of its own lifting water. Botanists were divided then, but cohesion-tension is now the textbook explanation.

![Joly was already known as a physicist; Dixon was a young botanist at the time. AI-generated still.](https://assets.planetpast.com/a/a6/a6f499587882a992.jpg)

- **3 ×**: normal air pressure, inside the tube

> Tensile properties of water enable trees to lift the fluid without exerting any effort whatsoever. (The Scientist, summing up Dixon and Joly’s claim)

Chapter II · Pulled from the top

#### The cohesion-tension theory

The Scientist: in 1895 the Irish physicist John Joly and the young botanist Henry Dixon published their paper in Philosophical Transactions of the Royal Society B (vol. 186). They enclosed a maple branch in a thick glass tube, its cut end protruding into a vial of water, and watched it move water against triple normal atmospheric pressure. Botanists were then divided over whether trees spend energy to lift water; Dixon and Joly argued the tensile properties of water do it without effort.

The apparatus in the scene is a simplified sketch, not a copy of theirs.

Sources: [The Scientist: 19th-century experiments explained how trees lift water](https://www.the-scientist.com/19th-century-experiments-explained-how-trees-lift-water-32093); [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory)

## Chapter III · Fragile threads

### Pipes made of dead cells
*Chapter III · Fragile threads*

The tree’s plumbing.

The water travels through wood, in a tissue called xylem. Its pipes are made of cells that die when they mature, leaving hollow tubes with walls stiffened by lignin, the tough substance that makes wood hard. Stiff walls matter, because the pull would squeeze soft pipes flat, like a straw when you suck too hard. In conifers such as redwoods, the pipes are narrow cells called tracheids, joined through tiny openings called pits. Watch water climbing from cell to cell. In a tall tree, these threads of water stretch more than a hundred metres, and must stay unbroken.

![Flowering trees add wide “vessels” made of cells open at both ends; conifers have none. AI-generated still.](https://assets.planetpast.com/a/34/34e367e3422bba33.jpg)

- tracheids: narrow, linked through pits; the only kind in conifers
- vessel elements: wide, joined end to end; not in conifers

- **dead**: the cells, once mature: only walls remain
- **> 100 m**: a continuous water column in the tallest trees

Chapter III · Fragile threads

#### Xylem

Vessel elements and tracheids lose their living contents at maturity and work as dead, hollow cells with strongly lignified walls; side walls carry pits that connect neighbouring cells. Vessel elements, open at both ends, are absent in conifers, which rely on tracheids alone. Raven Biology (LibreTexts): xylem vessels and tracheids are structurally adapted to cope with large changes in pressure.

The cells in the scene are drawn far larger than real tracheids.

Sources: [Wikipedia: Vessel element](https://en.wikipedia.org/wiki/Vessel_element); [LibreTexts Biology (Raven Biology): Movement of water and minerals in the xylem](https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map:_Raven_Biology_12th_Edition/36:_Transport_in_Plants/36.02:_Water_and_Mineral_Absorption/36.2.1:_Movement_of_Water_and_Minerals_in_the_Xylem)

### When the thread snaps
*Chapter III · Fragile threads*

Air bubbles in the pipes.

Pull too hard on a water thread, though, and it can snap. A tiny bubble of gas appears, the water springs away from it, and the pipe fills with air and vapour. This is cavitation. The bubble that blocks the pipe is called an embolism, and that pipe can no longer carry water. The harder the leaves pull, the more likely this becomes, which is one reason very tall trees live close to their limit. A trunk holds a great many pipes side by side, so losing a few does not stop the flow. Watch a thread break, and the water carry on through the others.

- **≈ 21 MPa**: tension reported to break a water column
- **> 1.6 MPa**: xylem water still unbroken beyond this, in a spinning test

- cavitation: the thread snaps and a bubble forms
- embolism: the bubble then blocks that pipe

- **1 pipe**: blocked: water keeps flowing in its neighbours
- **≈ 1.9 MPa**: pull estimated for a 113 m tree, see Chapter IV

Chapter III · Fragile threads

#### Cavitation

LibreTexts: gas bubbles can form in the xylem by cavitation, interrupting the continuous stream of water and causing a break termed an embolism; in a centrifuge experiment xylem water avoided cavitation at negative pressures beyond about 1.6 MPa. Raven Biology (LibreTexts) adds that, in flowering trees, small perforations between vessel elements reduce the number and size of gas bubbles; redwoods, as conifers, have no vessel elements.

Bubble sizes in the scene are illustrative.

Sources: [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory); [LibreTexts Biology (Raven Biology): Movement of water and minerals in the xylem](https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map:_Raven_Biology_12th_Edition/36:_Transport_in_Plants/36.02:_Water_and_Mineral_Absorption/36.2.1:_Movement_of_Water_and_Minerals_in_the_Xylem)

## Chapter IV · The tallest trees

### How tall can a tree grow?
*Chapter IV · The tallest trees*

A drought at the top.

Every extra metre of height adds to the pull the top leaves need, because the water must be held up against gravity and dragged through narrow pipes. In 2004, a team led by George Koch climbed the tallest redwoods in California. Near the top, the needles were smaller and more crowded, living in near-constant drought even though the soil below was moist. From those measurements, they calculated a maximum height for coast redwoods of about one hundred and twenty-two to one hundred and thirty metres. Watch the tree grow, and its top dry out.

![Wind damage and lightning can also stop a tree long before the water limit. AI-generated still.](https://assets.planetpast.com/a/2a/2a63df77a955131e.jpg)

$$\Delta p_{\text{gravity}} = \rho\, g\, h \approx 0.01\ \text{MPa/m}$$
- $h$: height of the water column

Gravity alone; friction in the narrow pipes adds more on top.

- **112.7 m**: tallest tree then measured
- **122–130 m**: predicted maximum

Chapter IV · The tallest trees

#### The limits to tree height

Nature News (19 Apr 2004): George Koch of Northern Arizona University, with S. C. Sillett, G. M. Jennings and S. D. Davis, climbed the tallest redwoods in Humboldt Redwoods State Park. Gravity and friction limit how high water can be pulled; leaves at the top live in effectively constant drought and are small and crowded. They calculated a maximum of about 122–130 m for coast redwoods. Koch: “We are not saying they will grow that tall; we are saying they can.”

ρgh with ρ = 1000 kg/m³ and g = 9.8 m/s² gives 0.0098 MPa per metre. The tree in the scene is drawn to its height scale only.

Sources: [Nature News: Height limit predicted for tallest trees (19 Apr 2004)](https://www.nature.com/news/2004/040419/full/news040419-5.html); [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory)

### The tallest tree alive
*Chapter IV · The tallest trees*

And where it gets extra water.

The tallest tree known today is a coast redwood named Hyperion, in Redwood National Park in California. It was found in 2006 and measured at one hundred and sixteen metres in 2019. That is still below the predicted limit. Lifting water that high takes a pull of about two megapascals, roughly twenty times the push of the atmosphere on a suction pump. Redwoods have help. Their tops reach into the coastal fog, where they can take up water straight from the air, and the fog keeps the forest cool and shaded.

- **116.07 m**: measured in 2019
- **25 Aug 2006**: found by Chris Atkins and Michael Taylor

- atmosphere at sea level: ≈ 0.1 MPa
- a 113 m redwood (LibreTexts): ≈ 1.9 MPa

![Coast redwoods grow only in a narrow coastal strip, from central California to southern Oregon. AI-generated still.](https://assets.planetpast.com/a/7c/7c8685dc338fd979.jpg)

Chapter IV · The tallest trees

#### Hyperion and fog

Guinness World Records: the tallest living tree is Hyperion, a coast redwood (Sequoia sempervirens) in Redwood National Park, California, measured at 116.07 m in 2019 and discovered on 25 August 2006 by Chris Atkins and Michael Taylor. LibreTexts: a pull of at least about 1.9 MPa is probably needed to lift water to the top of a 113 m tree. Vox: redwood canopies reach into fog layers, where they can absorb water directly from the air, and the fog shades and cools the forest.

1.9 MPa ÷ 0.1 MPa ≈ 19, rounded to “about twenty”. Hyperion’s exact location is kept secret to protect it.

Sources: [Guinness World Records: Tallest tree living](https://www.guinnessworldrecords.com/world-records/tallest-tree-living); [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory); [Vox (via DNYUZ): California’s tallest and most iconic trees are getting heatstroke (11 Oct 2026)](https://dnyuz.com/2026/10/11/californias-tallest-and-most-iconic-trees-are-getting-heatstroke/); [Science News: When climate change brings the heat, what happens to a mighty redwood? (12 Oct 2026)](https://www.sciencenews.org/article/climate-change-heat-redwood-temperature)

### Too hot to drink
*Chapter IV · The tallest trees*

The new redwood study.

Now back to the news. Todd Dawson of UC Berkeley, who was not part of the study, says coast redwoods are adapted to a narrow band of temperatures, roughly eight to twenty-seven degrees, and that fog has declined by thirty to forty percent. In the study's heat waves, the young trees in Mendocino County kept their stomata closed to save water. That also kept carbon dioxide out, and without evaporation to cool them, some needles ran up to ten degrees hotter than the air. In the lab, photosynthesis fell even when branches stood in water with their pores open, so heat itself slows the needles. They recovered after the heat passed, but where lasting harm begins is not yet known.

![UC Davis notes that heat also burns off the coastal fog the trees rely on. AI-generated still.](https://assets.planetpast.com/a/b3/b3f2ff94496fed45.jpg)

- saves water
- stops carbon dioxide getting in
- loses the cooling from evaporation

![Needles were sampled about 5 m up; on trees over 100 m tall, even the lowest branches are hard to reach. AI-generated still.](https://assets.planetpast.com/a/b8/b865c0e6dec216c9.jpg)

Chapter IV · The tallest trees

#### The heat study

Vox: UC Davis researchers led by PhD student Lily Klinek measured leaves twice a month over two years in Mendocino County; in extreme heat the leaves kept their stomata closed, stopping carbon uptake, and regained their capacity after the heat passed. Todd Dawson (UC Berkeley, not involved in the study) puts the trees’ adapted range at about 8–27 °C and says fog has declined 30–40%. Science News: in the lab, photosynthesis still fell in branches kept in water with stomata open. Klinek says the threshold for irreversible damage is unknown.

One study of young trees at one site. The leaf in the scene is schematic; its temperatures follow the study’s reported range.

Sources: [Vox (via DNYUZ): California’s tallest and most iconic trees are getting heatstroke (11 Oct 2026)](https://dnyuz.com/2026/10/11/californias-tallest-and-most-iconic-trees-are-getting-heatstroke/); [Science News: When climate change brings the heat, what happens to a mighty redwood? (12 Oct 2026)](https://www.sciencenews.org/article/climate-change-heat-redwood-temperature); [UC Davis: Coast redwoods slow their “breathing” and “eating” when temperatures spike (28 Sept 2026)](https://www.ucdavis.edu/climate/news/coast-redwoods-slow-their-breathing-and-eating-when-temperatures-spike)

## Epilogue

### Powered by the sun
*Epilogue*

A pull from the top, and its limits.

So a tree is not a pump: the sun pulls water up unbroken threads, from the leaves all the way down to the roots. But it has limits: threads that can snap, a height where the top goes dry, and pores that must close when water runs short. Hotter summers and thinner fog press on all of them at once, and no one yet knows how the oldest giants, like Hyperion, will cope.

- evaporation at the leaf pulls the water
- cohesion keeps the thread whole
- stiff, dead xylem cells carry it

- 1895: Dixon and Joly propose cohesion-tension
- 2004: height limit of 122–130 m predicted
- 2006: Hyperion found
- 2026: first redwood heat study

- **?**: the heat at which redwood needles are harmed for good
- **?**: how old giants respond, untested so far

Epilogue

#### Sources

Every figure in this film comes from the sources below. The 2026 heat findings come from a single first study of young trees, reported in the news; the physics of water transport is standard textbook science.

Stills are AI-generated illustrations, not photographs.

The 3D scenes are schematic: sizes, speeds and molecules are not to scale.

Sources: [Science News: When climate change brings the heat, what happens to a mighty redwood? (12 Oct 2026)](https://www.sciencenews.org/article/climate-change-heat-redwood-temperature); [UC Davis: Coast redwoods slow their “breathing” and “eating” when temperatures spike (28 Sept 2026)](https://www.ucdavis.edu/climate/news/coast-redwoods-slow-their-breathing-and-eating-when-temperatures-spike); [Vox (via DNYUZ): California’s tallest and most iconic trees are getting heatstroke (11 Oct 2026)](https://dnyuz.com/2026/10/11/californias-tallest-and-most-iconic-trees-are-getting-heatstroke/); [LibreTexts Biology (Botany, Ha, Morrow & Algiers): Cohesion-tension theory](https://bio.libretexts.org/Bookshelves/Botany/Botany_(Ha_Morrow_and_Algiers)/04:_Plant_Physiology_and_Regulation/4.05:_Transport/4.5.01:_Water_Transport/4.5.1.03:_Cohesion-Tension_Theory); [LibreTexts Biology (Raven Biology): Movement of water and minerals in the xylem](https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map:_Raven_Biology_12th_Edition/36:_Transport_in_Plants/36.02:_Water_and_Mineral_Absorption/36.2.1:_Movement_of_Water_and_Minerals_in_the_Xylem); [Wikipedia: Vessel element](https://en.wikipedia.org/wiki/Vessel_element); [The Scientist: 19th-century experiments explained how trees lift water](https://www.the-scientist.com/19th-century-experiments-explained-how-trees-lift-water-32093); [Nature News: Height limit predicted for tallest trees (19 Apr 2004)](https://www.nature.com/news/2004/040419/full/news040419-5.html); [Guinness World Records: Tallest tree living](https://www.guinnessworldrecords.com/world-records/tallest-tree-living); [USGS Water Science School: Evapotranspiration and the water cycle (PDF copy, Columbia IRI)](https://fdacourse.iri.columbia.edu/documents/M1U2_Clouds/Clouds_Readings/S3_Clouds_Readings/S3_Evapotranspiration_The_Water_Cycle_USGS.pdf)