Sap Rise in Spring

Barry Meatyard Barry.Meatyard at CSV.WARWICK.AC.UK
Fri Oct 4 03:08:28 EST 1996

Dear Plant Edders,

I've followed the correspondence on this with interest and would like to
offer a couple of observations.  Like John Hewitson, I've seen exudate from
a Walnut stump - in this case NOT a distal branch but the main trunk cut
off as close to the ground as a chain saw allows. The stump was about
30-40cm across as I remember and went on seeping for about a week after it
had been cut. Later when the main part of the stump was removed (but almost
certainly leaving some roots behind) and the site levelled the earth
remained damp on the surface even after neighbouring disturbed earth had
dried out.  This would suggest that in this case at least the stem is NOT
involved as David Hershey suggests, and whatever is happening is going on
in the roots.

I've also experienced at first hand exudate from sycamore (Acer
pseudoplatanus) which formed a dense hedge down one side of the garden of a
house I used to live in in Kent UK. I did some serious surgery on the hedge
to cut it back (it was a few years ago and I can't remember the time of
year - I suspect it was towards the autumn (fall) as I wouldn't normally do
that sort of work any earlier - certainly not in the spring because of
nesting birds - and I can remember leaves being around. The cut stumps
ended up between 1m - 2m high and 10-15cm in diam.  They dripped copiously
with the liquid appearing to come from the outer parts of the stems but I
couldn't establish whether this was coming from the very outer sapwood or
the phloem. It didn't taste sweet.

It's all been very interesting......


Dr.Barry Meatyard                       Tel: 01203 524228
Science and Plants for Schools          Fax: 01203 523237
Institute of Education                  Email: barry.meatyard at
University of Warwick

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