Why don't untapped maple trees explode?

**JWest** · Oct7-05, 03:14 PM

In my food and culture/biology class, our teacher played an audio file about untapped maple trees exploding, but after it was over, she told us it was an April Fool's prank. However, I am curious to know. Why don't untapped maple trees explode?

**Moonbear** · Oct7-05, 05:04 PM

What would your reasoning be why they should? Otherwise I don't even know where to begin to answer this question.

**pattylou** · Oct7-05, 06:24 PM

LOL...

I think tapping a maple tree is sorta like drawing blood from a person.

I give blood regularly, but my husband doesn't, and so far he hasn't exploded.

**sssddd** · Oct7-05, 06:30 PM

is this even the right place ask this kind of question.

**pattylou** · Oct7-05, 06:36 PM

Yes. Plants have biology too.

**arildno** · Oct7-05, 06:41 PM

Originally Posted by JWest

In my food and culture/biology class, our teacher played an audio file about untapped maple trees exploding, but after it was over, she told us it was an April Fool's prank. However, I am curious to know. Why don't untapped maple trees explode?

I suggest you read Brian Aldiss' brilliant Helliconia trilogy.
You'll be in for a real treat..

**Ouabache** · Oct7-05, 07:39 PM

Why don't untapped maple trees explode?

An inquisitive mind is a good thing. That is an important quality to study science. I've been asked a similar question about mosquitos. If you let one bite your arm and they take a drink, if you tighten your arm and increase the pressure in your blood vessels, will the mosquito explode?

Let's tackle your question.. It seems you are wondering about the pressure of the maple sap that flows in the springtime. The sap flows in the xylem (also called sapwood) and in early spring, it is due to root pressure. Because there are more solutes inside the roots compared with outside the roots, by osmosis water external to the roots, will be drawn in and rise up through the xylem. Later in the season, the leaves unfurl and transpiration (vapor transfer via the stomata) cause a negative pressure in the xylem and draws the sap up into the tree. Angiosperms (of which maple is a member) appeared on earth about 100 million years ago ref. They have evolved this nice method of drawing nutrients up into the tree where they are needed. To my knowledge, none have been observed to explode from the pressure of the sap. The reason is that the pressure is too low compared with the restraining forces of the vessel (wood in the tree).

Root pressure in trees can range from 0.1 to 0.6 MPa ref (0.1MPa = 1 atmosphere pressure, or the amount of pressure our own atmosphere exerts at sea level).

**pattylou** · Oct7-05, 08:01 PM

Originally Posted by Ouabache

An inquisitive mind is a good thing. That is an important quality to study science. I've been asked a similar question about mosquitos. If you let one bite your arm and they take a drink, if you tighten your arm and increase the pressure in your blood vessels, will the mosquito explode?

Let's tackle your question.. It seems you are wondering about the pressure of the maple sap that flows in the springtime. The sap flows in the xylem (also called sapwood) and in early spring, it is due to root pressure. Because there are more solutes inside the roots compared with outside the roots, by osmosis water external to the roots, will be drawn in and rise up through the xylem. Later in the season, the leaves unfurl and transpiration (vapor transfer via the stomata) cause a negative pressure in the xylem and draws the sap up into the tree. Angiosperms (of which maple is a member) appeared on earth about 100 million years ago ref. They have evolved this nice method of drawing nutrients up into the tree where they are needed. To my knowledge, none have been observed to explode from the pressure of the sap. The reason is that the pressure is too low compared with the restraining forces of the vessel (wood in the tree).

Great, except that you collect sap (maple water) in the fall ...

Practically, you should not tap a tree smaller than a particular size, and not more than with one sugar-water spigot....

How would any of the above change the answer, if at all?

**Ouabache** · Oct7-05, 08:13 PM

Originally Posted by pattylou

Great, except that you collect sap (maple water) in the fall ...

Hmmmmm

I've only seen taps on the sugar maple trees in early spring when the nights are cold and days are warm. Shortly thereafter, you can visit the sugar camps and watch them simmer the sap into syrup.

(Sidenote: you can tap any maple tree to make syrup, but the sugar maple's (Acer saccharum) sap, has the highest concentration of sugar (~ 2%)

You are right, small trees should not be tapped. Typically trees are tapped when their trunk diameter is minimum of 10 inches measured four feet above the ground ref

**pattylou** · Oct7-05, 08:17 PM

Maybe my mom taught me wrong? She grew up in Australia, she may have had it backwards....

**pattylou** · Oct7-05, 08:20 PM

Google has me wrong and you right. I stand corrected.

I wonder if we killed a few trees in ignorance.... I know we successfully tapped a few trees in the woods in the fall, but didn't pay attention to whether they grew well the next year.

thanks Oubache!

**Ouabache** · Oct7-05, 08:51 PM

That's okay, as a Boilermaker you're talented with a creative thought process

Let's hear more about the maple syrup

~~Lapin Dormant~~ · Oct8-05, 11:57 AM

Hey hows about tapping those Golden Birches in the spring too, hear that they can make pretty good sap-syrup as well, run well too. (juicy)

**Ouabache** · Oct18-05, 02:51 AM

Golden Birches? Are you referring to Betula ermanii? According to this source, gold birch doesn't have any edible uses.