Terminology

Last Monday Dave S. and I walked the creek. Somewhere along the way I said something about xylem and he said something about phloem. I knew xylem was the wood under the bark but Dave wasn't sure what exactly phloem was. Between us we guessed that phloem was the innermost portion of the trunk.

After writing yesterday's post I went looking for information on Wikipedia. "Tree anatomy" got me zilch. "Tree" was the winner. There I found that xylem is indeed the woody part of the tree. It carries water and minerals upwards. The phloem includes the cambium, where growth occurs, the structures on either side of it, and the bark. It carries some water, sugar and nutrients downwards from the leaves to the roots.

I was reintroduced to a word I knew a long time ago: girdling. That's what beavers do to trees. They remove the bark, phloem actually, all the way around a trunk. This prevents the roots from getting any nutrients, ultimately killing the tree. The article on girdling also mentioned that fruit growers employ the girdling technique to grow over sized fruit. They will girdle a branch and remove all but one fruit from it. Because there is no normal "sink" for the nutrients from the leaves, they are forced into the only one remaining -- the fruit.

And that's the end of today's lesson.