Friday, November 20, 2015

Biology: Botany

 Last week's classes were both about Botany. 

We looked at leaves, their structure and function, and how to identify trees by their leaves and branches, thanks to my trusty dichotomous keys!

We also did some leaf chromatography by rubbing leaves with stones onto filter paper. 

We labeled the strips and put the ends into rubbing alcohol.

As the alcohol traveled up the strips, it spread out the components of the leaves

 While the leaves started out green (yes, I had to find green leaves in November!), they separated into green, yellow, red, and purple.

Very cool!

 We also looked at roots and stems (tree trunks are modified stems).

The kids were particularly interested in the idea that it's the outside of the tree that's alive, and that most of the living tree is in the bark (although not the outermost layer of bark).

We talked about xylem and phloem, the "blood vessels" of plants.  The phloem "flows" down and the xylem... doesn't.  At least, that's how I keep them straight!

I would have done the celery and food coloring if I'd thought of it.  Maybe next time!

And they were interested in the cambium, the layer which makes both kinds of tubes, and how it creates the rings by which you can tell the age of the tree (or branch, actually).

And roots were fun!  It turns out the kids didn't realize that marshmallows were made from the roots of the marsh mallow (a common flower in swampy areas around here).

I told them, to help them remember, I would give them each one marshmallow.

They liked it, I think.  I couldn't really tell what they were saying.

Nowadays, of course, most marshmallows are made from gelatin instead of marsh mallow roots, but real licorice and real root beer still come from real roots!

We also talked a bit about plant tropisms, because that's always interesting.

And that's about it for Botany!

Would you believe we only have two weeks of Biology left?!

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