UKTC Archive

Re: the penny dropped.....

Subject: Re: the penny dropped.....
From: Julian Morris
Date: Jan 04 2019 16:53:44
"Physiology of Woody Plants" refers to them as 'adventitious aerial roots'.

I had a case last year where the base of a mature Poplar got buried a few 
years ago by 2' of chippings. It pushed out a set of roots, and when the chip 
rotted away they remained a foot above the original root collar. Pic attached 
hopefully.

There seems to be some suggestion that once initiated from primordia aerial 
roots can continue without external water or nutrition until they reach soil. 
So ageing of aerial roots may not mean decaying wood was present throughout 
their transit from development to soil. Or it might. It may depend on 
species. For example, Ficus manages it frequently. "Physiology of Woody 
Plants" lists genera that commonly produce stilt roots. To which list I would 
add Betula and Taxus.  

Julian A. Morris - Professional Tree Services
jamtrees.co.uk  and  highhedgesscotland.com
0778 XXX XXXX - 0141 XXX XXXX


Sent: Friday, January 04, 2019 at 4:41 PM
From: "Jon Heuch" <jh@xxxxxxxx.co.uk>
To: "UK Tree Care" <uktc@xxxxxx.tree-care.info>
Subject: the penny dropped.....

I've been looking through various references on veteran trees to see if the
adventitious root systems internal to the main stem that we sometimes see in
hollow old trees (hornbeam, yew, other species?) has a special term..but can
hardly see any mention of them.

 

Anyway every time I've seen them I've wondered how they developed and what
process allowed roots to develop above ground and survive whilst they grew
to the soil surface below ...and why I couldn't find any half grown roots.

 

I am sure others must have seen evidence as shown in the attached photo i.e.
the internal root developing in decaying heartwood but it was a first for
me, and a clear explanation for my observations. [the photo is upside down
so rotate thru 180 degrees]

 

1.    We would not expect to see half grown roots as they have developed
within the decaying heartwood, at a time when the decaying wood is soft
enough to allow root penetration and provide both nutrients, water & air
i.e. a suitable rooting environment. The root has to reach ground level
before all the decaying heartwood has gone.
2.    Once the tree is hollow the roots are less likely to form and grow.
3.    I assume, some types of decay may favour root development over
others (cubical brown rot over wet brown rot?)

 

Thus if the internal root was cored & rings counted it might provide some
indication of how long ago the tree had had decaying heartwood. I don't know
if such roots have growth rings...anyone any idea? Anyone tried to count
rings on roots?

 

Jon 

 




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