樹木的莖與根 Woody Stem / Woody Root

樣本來自刺槐樹，比較樹木莖與根的不同

1.樹木的莖有綠色皮層，根沒有綠色皮層。

2.樹木莖在活細胞中儲存適量的澱粉。樹根在活細胞中儲存大量澱粉。樣本用I²KI染色，會使澱粉粒變成紫色。在樹根可以看到更多紫色部份。

3.樹木莖有髓心，樹木根沒有。

4.樹木莖有大量木質素，根部沒有。如果你用鋸子鋸樹幹，然後切樹根，你會發現樹幹比較難鋸。

5.在照片中，可以看到樹根維管束更大且更分散，與莖相比，根難區分生長增量。

樹木根部功能

1. 固定樹木。

2. 輸送游離水和溶解在其中的物質。

3. 儲存能量儲備並保持水分。

4. 製造樹木生命所必需的物質

Woody Stem / Woody Root

This sample is from a Honey Locust Tree.  Gleditsia triacanthos.

Some anatomy differences.

1.  Woody stem has a green cortex, the woody root has a cortex that is not green.

2.  Woody stem stores a moderate amount of starch in living cells.  Woody roots store a large amount of starch in living cells.  This sample was stained with I²KI.  The stain turns starch grains purple.  You can see more purple to black in the woody root.

3.  The woody stem has a pith.  The woody root does not have a pith.

4.  The woody root has a moderate amount of lignin.  The woody stem has a much greater amount of lignin.  If you were to cut a woody stem with a hand saw and then a woody root, you would see that the woody stem would be much harder to cut due to a greater amount of the cementing substance called lignin.

5.  In this sample you can see that the vessels in the woody root are larger and more diffuse making the woody root more difficult to differentiate between the growth increments compared to the stem.

The list goes on.

Woody roots are organs that:

1. Anchor the tree.

2. Transport free water and substances dissolved in it.

3. Store energy reserves and hold water.

4. Make substances essential for the life of the tree.

資料來源:

http://www.treedictionary.com/DICT2003/tree_pruning/stem_root/index.html

mage and Text Source - TREES, ASSOCIATES, and SHIGO (2 CD set).