I’m going to revisit this topic.  One of my first posts was about photosynthesis, but back then, my blog posts were 2 unfortunate things: wayyyyy too long and not nearly illustrated enough.  So here we go.

Plants do this thing called photosynthesis, which translates to “using light to make stuff.”  We all know that plants use light from the sun, but what are they doing with that energy?  What are they making, and what are they making it out of?

This is a seed.

It is tiny.

How on earth does this seed turn into this tree?

Where did all this “stuff” that makes this tree come from?  What are the building blocks?

If you ask what trees are made of, most people will say water and soil.  Let’s examine this.

1. Water just happens to be correct. Plants use water in photosynthesis and they store large amounts of it in each cell to make them sturdy. You can see evidence of this if you have cut flowers out of water for too long. They get droopy and depressed as the water in each cell evaporates, but as soon as you put it in a vase of fresh water, it draws that water into all the cells, and it perks up.

It sure looks happy for a severed flower head. It’d be really cool if this worked with human body parts too.

2. Soil. Okay, yes, plants usually need soil, but that doesn’t contribute to its mass–the “stuff” that makes a tree so big. Don’t believe me? Well, when you plant a seed in a pot, and the seed grows into some lovely plant, isn’t the soil still there? The soil isn’t contributing to the size of the plant. No, sir. It’s just there for support.

So if it’s not soil, what are plants made of? Where are they getting all the “stuff”? We get our “stuff” from the food we eat, but plants don’t eat anything. That’s what makes them plants. (Okay, yes there are carnivorous plants, but I’ll talk about that in another post.)

I won’t keep you in suspense any longer. Plants make their stuff from CO2, carbon dioxide, from the air.  This is the carbon source for the billions of cells that make up the plant’s body. (We get our carbon by eating plants and other animals.)

This is the equation for photosynthesis.  It probably looks somewhat familiar, but hopefully it makes a little more sense now.

The problem is that even if someone memorizes the equation for photosynthesis, they still think that plants are made of soil.  The idea that AIR could create a massive, sturdy tree is totally counterintuitive.    Most people think that air is nothing–just emptiness. But tell that to someone whose house is blown away by a tornado.  You know what caused the damage?  AIR.  Air has mass.  Air has stuff.  I swear.  I’m gonna make some billboards with PSAs for this:

So yes, this is a little strange.  Plants are literally pulling building blocks out of thin air.  They’re just clever like that.