North American Fruit Explorers mailing list at ibiblio

["Lon J. Rombough" <lonrom@hevanet.com>]

Heron:
Where did THIS come from?  You've asked something that would take a small book to answer.
Here are a FEW points just to get the ball rolling.
1.  Some "adventitious" buds are really very old buds buried deep in the wood.  Laid down when the tree is young, they usually don't push unless something very drastic happens to the tree.  These are the ones that produce sports most often as the older the bud, the more likely it has been hit by radiation, etc. during it's existence, causing a mutation.  A great number of bud sports of Red Delicious trace back to a severe winter in Washington in the 1950's that froze back many trees, causing old buds to push from deep inside the wood.
2.  True adventitious buds arise from undifferentiated (callus} tissue, usually from near a wound.
3.  Many plants have different layers of tissue that are actually genetically different.  In old types of thornless blackberries, only the surface layer was genetically thornless, the internal tissues were thorny.  Cut a root and a new shoot would push from an internal layer of tissue that was genetically thorny, giving rise to a thorny shoot.  Use "Chimeras in plants" in a search engine and you should find more about this.
4.  In seedling trees, most trees go through a juvenile stage in which they may actually be different in appearance from the adult stage.  As the tree grows it  becomes mature, but the juvenile stage is still there.  Case in point, many Eucalyptus trees have a juvenile stage with round leaves, but develop leaves of other shapes as they mature.  But cut the tree down to the height at which it was still juvenile and the new shoots will be juvenile for a while, having to grow back out of it.  
5.  Cut a tree root and force a shoot from it and the shoot will often be juvenile and have to grow up just like a seedling, to get to the mature phase all over.  One good thing is that cuttings from juvenile trees can usually be rooted more easily than ones from mature trees.  This has been used to propagate trees from cuttings that usually don't work that way.  Layer a mature shoot to get it on it's own roots.  Grow it until you can get root cuttings from it and grow juvenile phase trees from those roots.  Take cuttings of the juvenile phase trees and root them.

End of lecture for now.
Someone else can add other stuff.
-Lon Rombough
Grapes, writing, consulting, my book, The Grape Grower, at http://www.bunchgrapes.com  Winner of the Garden Writers Association "Best Talent in Writing" award for 2003.
On Mar 20, 2005, at 5:59 PM, Heron Breen wrote:

Okay, maybe not news to some, but interesting to me, so I thought I would write in:
Terminal Buds (end of shoot wood bud) and Axillary buds (bud situated in area where 
leaf stem meets the shoot or branch) are both connected to the pithe of a Tree 
vascular system. An Adventitous bud (bud arising "randomly" from areas on older 
parts of the Tree and not accompanied by a leaf) is NOT connected to the pithe. 
This seems to make intuitive sense to me, as the pithe represents the conglomerated 
metabolic history of a tree, and any bud arising from this layer would seem natural 
to continue this expression. Meanwhile, the adventitous buds are the ones usual 
responsible for mutations, ie sports etc, and are arising from where? Is it still 
in contact with the phloem? Arising from previous years' growth layers? 
With roots, I see the term adventitous shoots/buds being used in relation to root 
cuttings or suckers. These shoots/buds originate in the pericycle and vascular ray 
tissue, and a few other areas I can't spell. I haven't been able to track down the 
area(s) in the tissue above the root collar that adventitous buds arise from. Does 
the word phellogen mean anything to folks? 
Another curious query: does the meristem activity in the three types of buds 
mentioned above differ?
I LOVE the "scientific" use of the word "arise" in relation to celluar activity. 
Reminds me of the certain religious writings...
Thanks for any and all feedback, just trying to fill in the cracks,
Heron Breen
maine, zone 4 



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