Re: Philodendron aerial roots

I grow a lot of orchids, and I know that this is definitely the case with
these plants.. If, when repotting, you bury roots that had been growing
outside the medium, they tend to suffocate pretty quickly.. 

At 09:33 PM 11/18/97 -0600, you wrote:
>>..  Sure, aerial roots
>>>have a different epidermal layer than ones that are in potting media but
>>>that is only because they are in air and not in media.  But, when they find
>>>some type of media...  they change.
>>That's my point. My understanding is that subsurface roots are different
>>than aerial roots, even if the two zones exist on the same root. Burying the
>>aerial portion often leads to rot of the root. If the aerial portion hits
>>substrate and changes...I think the root is ok. Does this make any sense?
>This makes perfect sense from a biological standpoint.  The root tip, just
>like the growing tip, has what are termed meristem cells, that is, cells
>that are actively dividing but may not have differentiated into specific
>cell type (leaf, stem, root hair or whatever), so probably when this
>meristem area first contacts some type of substrate suitable for rooting,
>the cells behave appropriately (i.e. begin to differentiate).  Now if you
>bury this area rather than letting the root "feel" the ground first, you
>may well short circuit the normal rooting mechanism, leading to the
>observed rot.
>Don Martinson
>Senior Research Associate
>Department of Medicine
>Division of Endocrinology, Metabolism and Clinical Nutrition
>Medical College of Wisconsin, FMLH-West
>9200 W. Wisconsin Ave.
>Milwaukee, WI  53226
>(414) 259-3817

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