How do trees make sap

How Do Trees Make Sap?

SCIENCE — Life Science

Have You Ever Wondered...

  • How do trees make sap?
  • How much sap does it take to make syrup?
  • When is the best time to get sap from a maple tree?

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  • Plants,
  • Science,
  • Syrup,
  • Tree,
  • Sap,
  • Tap,
  • Sugar Maple,
  • Sapwood,
  • Photosynthesis,
  • Carbohydrate,
  • Starch,
  • Sugar,
  • Sucrose,
  • Spring,
  • March,
  • Weather,
  • Freeze,
  • Thaw,
  • Cycle,
  • Temperature,
  • Freezing,
  • Pressure,
  • Positive,
  • Negative,
  • Suction,
  • Force,
  • Water,
  • Roots,
  • Carbon Dioxide

Today’s Wonder of the Day was inspired by Ms. Rye's 5th Grade class from Sioux Falls. Ms. Rye's 5th Grade class Wonders, “How do trees create sap?” Thanks for WONDERing with us, Ms. Rye's 5th Grade class!

You're sleeping peacefully when suddenly the sound of pots and pans gets you stirring. You're able to drift back to sleep for a few minutes, but it's not long before you're pulled into full consciousness by your nose.

As you sit up in bed, you sniff the air and recognize the unmistakable smell of pancakes! Your mouth begins to water as you jump out of bed and head to the kitchen.

It won't be long until you're seated at the table before a stack of flapjacks, ready to soak them in that sweet and sticky substance that turns ordinary pancakes into a breakfast treat: syrup!

As you wait for your pancakes to be served, you take some time to WONDER about where that syrup comes from. Like the paper you write on at school, syrup comes from those tall, woody perennials you often take for granted. What are we talking about? Trees, of course!

You can't drill a hole in just any old tree and have syrup pour out. You can, however, tap certain kinds of trees, such as sugar maple trees, and collect gallons of sap at the right time of year.

Syrup makers use tree sap to make syrup. On average, it takes about 40 gallons of sap to make just one gallon of delicious syrup.

Sap inside a tree is a bit like blood inside the human body. Sap flows through a part of the outer tree trunk known as sapwood, delivering water, sugars, and nutrients throughout the tree.

Sap production begins in warm summer months when the process of photosynthesis creates carbohydrates that get stored in the tree as starch. The starch then gets converted to sugar in the form of sucrose that dissolves into the sap, which is stored for the winter.

When spring begins to arrive (often around the month of March), the weather provides just the right conditions to produce sap that can be collected to make syrup. Those special conditions consist of alternating freeze/thaw cycles in which temperatures drop below freezing at night and rise above freezing during the day.

The rising temperatures during the day create positive pressure within the tree that will force sap out of any holes in the tree. In addition to taps purposefully placed in the tree to collect sap, sap will flow out of broken branches or any other cracks or holes in the tree.

At night when temperatures fall back below freezing, negative pressure develops inside the tree. This creates a suction that stops the sap from flowing out of the tree. This suction force also pulls water through the tree's roots to replenish the sap. Experts believe these differences in pressure as a result of temperature fluctuations occur because of the expansion and contraction of carbon dioxide gas within the sapwood.

This cycle continues until temperatures stay above freezing, at which point sap will stop flowing and begin the sap production cycle anew. Scientists believe that the sap's main purpose is to provide nutrients to new leaves as they grow. In turn, those leaves will fuel the process of photosynthesis that starts the sap production process.

You may be WONDERing if drilling holes into trees is damaging. Using proper tapping procedures, trees sustain only minor wounds that are not damaging. Trees repair drill holes and heal in a matter of time.

Wonder What's Next?

Tomorrow’s exciting Wonder of the Day will take you on a trip to outer space!

Try It Out

Are you ready to tap into more WONDER? Find a friend or family member to help you check out the following activities:

  • Go for a hike with a friend or family member in a local park or forest. Can you find any sugar maple trees? If you're not sure what to look for, check out How To Identify Sugar Maple Trees online. If you can't find any sugar maple trees, make a list of the trees you are able to identify. You can use a tree identification guide from a local library. There are also plenty of online resources you can use. Take pictures of trees you find, including their leaves, and then try to identify them once you get home.
  • Ask an adult friend or family member to take you on a field trip to a local grocery store. What are you looking for? Maple syrup, of course! Locate the syrup and count the various different types of syrups available. How are they similar? How do they differ? Choose one syrup to try at home. You might also want to pick up some supplies to make pancakes or waffles. When you get home, cook up a hearty breakfast with maple syrup as the star!
  • While you're making pancakes, observe and investigate changing states of matter! Visit the From a Liquid to a Solid - Making Pancakes lesson at the PNC Grow Up Great Lesson Center for guidance.

Wonder Sources

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What Is Tree Sap and What Causes It?

Filled with nutrients and minerals, sap is the blood of a tree. It carries energy out into the branches when new buds are forming in spring-time. It comes in many forms; it can be that stuff that gets on your clothes and sticks to your car, or it might be perfect drizzled over pancakes. And if those things weren’t interesting enough for this curious substance, it has also been the subject of shocking photographs that swept the world thanks to disease.

There are a few reasons why you might come into contact with sap, with some being desirable and some not, but what is it and what does it do for the tree?

What’s In Tree Sap?

There are two separate substances usually lumped together under the label of sap; these are xylem and phloem. Xylem transports water, minerals and hormones from the bottom to the top of the tree in a long string formation. Each year the xylem channels die off and new ones are produced. When you fell a tree and are faced with those wonderful rings you are seeing the old xylem channels, one ring for each year of life.

Phloem, however, is the sticky sugary stuff we tend to come into contact with whether by accident or on purpose. This is made up of the sugars created by photosynthesis, which is then fed back into the tree and leaves as much-needed food during the growth period.

Trees That Produce Edible Sap

One very popular tree is the sugar maple (Acer saccarum). Its sap has a sugar content of up to 2% and they make a lot of it; it is tapped in late winter and early spring, with a healthy, good-sized tree producing as much as 15 gallons of heavenly sweetness. The sugar maple is the most prolific for sap production, but every maple produces edible sap with varying degrees of sweetness. Much is not commercially viable due to the lower yields but they are still commonly used for domestic purposes. In Korea the Gorosoe (Acer mono) is the most common source of sap; traditionally it’s used ‘raw’ as a hot beverage rather than boiled down into syrup.

As well as maples there are a few other trees that produce edible sap. The white walnut (Juglans cinerea), black walnut (Juglans nigra), heartnut (Juglans ailantifolia) and the English walnut (Juglans regia) will all yield tasty sap, with the heartnut boasting sugar levels comparable to the sugar and black maples. The sap of many birches is also very nutritious – while it’s low on sugar it’s a great source of minerals and natural antioxidants.

Why Do Trees Produce Sap?

The aforementioned uses of tree sap are undoubtedly positive; however our other interactions with it might not be so much fun. Often the reason we encounter sap on the outside of a tree is because something is wrong. Leaking sap on the bark can be a sign of disease, pests or damage. A common pest that causes damage to trees, and forces protective action, is the bark beetle. These burrow into the tree to lay their eggs under the bark layer. When the eggs hatch the larvae burrow start to carve out a network of deep burrows, and it usually requires chemical treatment to save the tree. However the tree’s own sap can often serve as an effective defense mechanism – the holes made by the burrowing adult beetle fill up with the sticky fluid, which can prevent it laying the eggs and even sometimes trap it.

Indirectly exposed sap can result in various mildews, as there are insects such as the mealybug and aphid which feed on the substance. They, in turn, exude their own sticky fluid known as honeydew and the presence of this can increase the occurrence of sooty mildew.

There is one particular showing of sap that created many stories of impending doom and apocalypse, however. Presented with images of trees leaking what appeared to be blood, the internet went into meltdown with fantastical stories about what might be causing it. A quick search of Google for “bleeding trees” will pull up some fascinating images if you have not seen them already, and there are some quite graphic shots of the stuff pumping forcibly from trees. But was there some sinister reason for these eruptions of deep red sap? Of course, much like blood pumps harder round our bodies as we exert ourselves, as does tree sap. If these trees are cut or damaged at the height of the sap production it can appear in spurts from the injury, and some species are well known as “bleeders”. It’s worth looking at the images if you ever need a reminder of just how surprising nature can be.

Removing Sap From Clothes, Skin, Cars and Other Items

One common complaint about sap is its famed ability to stick to things we’d rather not have it stick to. You can get covered in sap while doing yard work, exploring in the woods or even decorating the Christmas tree, and it’s always best to clean it up before it has a chance to harden. If caught while still sticky it can usually be removed without too much trouble. Skin and hair are two areas where contact can be tricky. Rub sticky skin with nail varnish remover to break the bond, then wash it away gently with warm soapy water. In hair your first reaction might be to chop it straight out, but that isn’t really necessary. Treat it like bubble-gum – coat the sap with peanut butter, massage it loose then wash your hair as normal.

Rubbing alcohol is great for removing sap from fabric; apply it to the affected area to loosen and remove the substance, then put the item through a warm wash.

Another way to utilize nail varnish remover is when sap drips on your car – something many of us have experienced. Do not apply directly to the paintwork, just soak some cotton wool and work it gently into the offending sap before washing your vehicle as usual. If the idea of applying nail varnish remover makes you uncomfortable another great option is WD-40, which is very unlikely to react with the paintwork at all. Once it has achieved its aim, simply wash it away with a solution of water and vinegar.

From your point of view sap can either be a nuisance or a delicious treat, but to your trees it’s vital. Look out for unusual leaks and consider sap activity when deciding when to trim, and if you have a maple on your property read up on how to tap it. If you have trees you’re going to have sap, so make the most of it!

How and why is juice extracted from trees? | Food and cooking

I started looking for what kind of drips are on the bark of various cherries, plums, apple trees and other fruit trees. It turned out that what we then chewed is called “gum”. Now people have already adapted for their use literally everything that the plants cultivated by them can give.

Grapevine sap, or "Tears of the Vine"


In the places of ancient viticulture, apiary, or vine juice, is used. In early April, when the vine awakens, before the buds swell, the flow of juices begins. The vine is cut obliquely, tilted and a vessel is placed to collect the liquid with healing properties.

Extracted must be stored in a refrigerator. Recommended for hypertension, good for gout, used to treat kidneys, liver, heart. Contains many vitamins, organic acids and trace elements. Excellent dietary supplement, suppresses appetite.

Milk tree

There are many strange plants in the Amazon. Among them is the "milk tree" - galactodendron (Brosimum galactodendron). It belongs to the mulberry family. Like many other representatives of this family, when the trunk is damaged, it secretes thick white juice.

Unlike the sap of other trees of the family, the sap of the cow tree is not only not poisonous, but even useful. The juice from the damage flows so actively that it fills the bottle in half an hour. The composition of this juice is very close to cow's milk. The locals call it "sorveira" or "nipple" and consume this juice with pleasure.

European researchers initially considered the sap of the tree to be poisonous due to its bitter taste. But studies of the composition showed its harmlessness. The locals have been cultivating this tree for thousands of years and have always drank and drink its delicious juice. By the way, the fruits of this tree are considered inedible. Only its juice is edible.

Milk tree sap is also boiled, as a result, a kind of wax appears on its surface. This wax is collected. It can be chewed like chewing gum and is also used to make candles.

This tree is also common in Venezuela. Moreover, it is argued that the milk given to them is sweet, and if its juice is boiled, a thick mass is obtained, very similar in taste to sweetened cottage cheese.

In addition to juices, people consume a large number of different gums collected from very different plants around the world.

Gum arabic (food additive E414)

Gum arabic - acacia resin
Photo: ru.

Extracted from the trunks of various types of acacia. Initially on Acacia nilotica and currently on Acacia senegal and Acacia seyal. About 80% of gum arabic is mined in Senegal.

Tree resin is used as an emulsifier in various recipes. It is used in marshmallows, marmalades, ice cream, in various creams.

Widely used in painting as a binder for glue paints. Included in watercolors, gouache, used in ceramics for attaching enamel to clay.

Carob bean gum (food additive E410)


Obtained from the seeds of the carob tree. Due to its resistance to low temperatures, it is used for making ice cream, a variety of frozen desserts, for cream cheeses or sauces.

Guar or pea tree (food additive E412)

Used as stabilizers, emulsifiers, thickeners in the production of ice cream and various desserts.

Manufactured in India, Pakistan, Australia, Africa, USA and Canada. It is considered a weight loss aid because it reduces appetite and is not absorbed in the intestines. And besides, it reduces the level of saturated fatty acids and bad cholesterol in the blood.



Gum that stands out on sets of lesions in plants of the genus Astragalus (Fabaceae). Plants of the genus are shrubs, semi-shrubs and herbaceous plants. The name comes from the Greek words tragos (goat) and akantha (thorn).

Astragalus species that secrete gum are mainly thorny shrubs of the subgenus Tragacantha, they are common in Eurasia (mountains of Central Asia and Western Asia) and in northern Africa.

Used in medicine, in the production of tablets, pills and lozenges as a binder and emulsifier. And besides, when printing patterns on fabric, in the confectionery industry. Even in the production of shoes - when gluing soles.

But all these undoubtedly very useful gums are not found in our gardens.

So let's go back to cherry gum , which we used to eat with pleasure in our childhood.
Gum secretion of the cherry tree

In various sources, it is written mainly about how gum secretion is harmful to an apple tree, cherry or apricot, and how to treat it. But one of the authors nevertheless bothered to note that this gum is not poisonous . (Ha! If not for that, we would have ended up in the hospital with the whole gang.) On the contrary, it is very useful, it causes a feeling of fullness, since it absorbs liquid in the stomach, swells and turns into a gel. And besides, it helps to lower the level of bad cholesterol in the blood, stabilizes sugar levels, helps with stomach diseases - thanks to the enveloping properties of the gel into which it turns in the stomach.

Ah, there were times! And the cherry gum seemed delicious, much better than the chewing gum, which didn't go on sale until about twenty years later.

Tags: tree sap, vine, healing properties, gum, tree resin

How does the sap get up the tree? - Children's encyclopedia Because.


Category: Botany

In humans and animals, blood circulates through the body driven by a powerful pump, which is the heart. Thus, each cell of the body receives all the substances necessary for its vital activity. Each part of the tree is also washed from the inside with a solution of nutrients in water - the sap of the plant. However, no tree has a heart. How, then, does the sap rise up the tree?

Science still cannot give an exact answer to this question. None of the theories that exist today offers a complete and final explanation of this phenomenon. Therefore, scientists are inclined to think that the movement of sap along the tree is carried out under the influence of several forces acting simultaneously.

The theory of osmotic pressure is the most widespread. The fact is that in all living organisms, a solution of nutrients enters the cells through thin membranes. This is because the concentration of dissolved substances on different sides of the membranes is different, and therefore, according to the laws of physics, it tends to equalize. Such a phenomenon (occurring, by the way, not only in wildlife) is called osmosis, and the difference in the concentrations of a substance on different sides of the membrane, which is the driving force of the process, is called osmotic pressure. Thus, the greater this concentration difference, the greater the amount of liquid transferred through the membrane.

The water and mineral salts necessary for plants to sustain life are found in the soil. Since their content there is higher than in the roots of trees, osmotic pressure arises, forcing moisture with salts dissolved in it to penetrate into the plant. Due to the same effect, the juice rises up the root into the trunk and further to the rest of the tree.

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