A Tree Grows... How?

Valorie's currently attending a seminar about teaching science at the middle-school level.

Yesterday, her instructor asked the following question:

"I have in my hand a Douglass Fir tree seed that masses 1 gram [I'm making this number up, it's not important].  I plant it in my yard, water it regularly, and wait for 20 years.

At the end of that time, I have a 50 foot tree that masses 1,000 kilograms [again, I'm making this exact number up, it's not important].

 

My question is: Where did the 999,999 grams of mass come from?"

 

I'm going to put the answer out to the group.  Where DID the 999,999 grams of mass come from in the tree.

The answer surprises a lot of people.  And it brings to question how much we actually know about science.

 

 

I'm going to change my comment moderation policy for this one.  I'm NOT going to approve people whose comments have the right answer, until I post my follow-up post tomorrow, because once the right answer's been given, it's pretty clear.  But I'll be interested in knowing the percentage of comments that have the right answer vs. the wrong answer.