At 4:13 PM -0500 11/12/97, John Hewitson wrote:
>The leaves are falling here in England too. All at once, with the first
>frosts of the winter this last fortnight.
>>Under our Wallnut trees (Juglans regia) I find there is no moss growing
>amongst the cobbles until outside the leaf-drip zone where a healthy carp=
=3D
>et
>of moss has grown. I doubt whether this is due to lack of light (the
>lowest branches are 10 ft up), I suspect that the amount of moisture is n=
=3D
>ot
>very different either. I have observed this under Holly (Ilex aquifolium=
=3D
>)
>too, where Winter aconites (Eranthis hyemalis) do not grow under the tree=
=3D
>>until clear of the leaf-drip. Aconites do however grow under a Beech tre=
=3D
>e
>(Fagus sylvatica).
>>Is this a well known fact, if so what is the explanation. Otherwise, wha=
=3D
>t
>do you think? Are there inhibitory chemicals in the water dripping off
>SOME leaves?
The popular choice for answering your question is
a chemical known as juglone that leaches from
leaves, bark, and fruit coverings of walnut.
ross
_______________________________________________________________
Ross Koning | koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA | fax: 860-465-4479
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