BUDS - How they open.


Buds are organs.  Buds are structures that are made up of embryonic shoots.   Starch is stored at the end of the previous growing season at the base or behind of the bud.  If this starch is not stored or the starch is not there in abundance in the spring, the bud will not open.

In the spring the starch stored at the base [or behind] of the bud is converted back to glucose and a turgor pressure is produced.   In other words in spring the starch is enzymatically converted back to glucose, which greatly increases the osmotic pressure.  This pushes the bud open.   Starch is one of the  primary substances that trees store their energy.  Starch basically is different from glucose by lack of a water molecule in starch. 




When starch is converted back to glucose the water molecule is added back.  

Meristems rarely store starch.  The cambial zone, which is a meristem, and buds do not store starch.  Starch is not soluble in water.  To be utilized, the starch is converted to simple sugars that are soluble in water.  The starch at the bud base provides the energy to start growth.





Sample to right was stained with I2-KI (iodine in potassium iodide) that stains starch grains purple.














Some Myths and half truths still in text books and being taught.

From 100 Tree Myths by Shigo and Trees, Associates

Myth 59. TO OPEN, BUDS REQUIRE FOOD FROM ROOTS.  Energy in the form of starch or other reserves are at the bud base the growing season before the bud sprouts.  Roots provide water and elements.  A tree can be cut in October or November in the north and the cut end put in a stream or pond.  The next spring, the leaves, flowers, and sometimes even fruit will form on the tree.  It is common practice to force twigs of flowering shrubs and trees.  Roots require all the energy they can store to support their root growth.

Another myth in books is that as water is absorbed in spring and it goes up and pushes the open.
Some books even state hormones have something to do with buds opening.  Trees do not have "hormones" they have "growth regulators".

See "BUDS"


John A. Keslick Jr.
Tree Biologist

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