PK wrote:
"Nick Maclaren" wrote in message
...

In article ,
Broadback writes:
|
| Just curious. As I understand it the evaporation of moisture is what
| draws the sap from the toots up the tree. Does this mean that the sap
| does not rise until the leaves unfurl? If so where do the leaves
obtain
| the energy to be "kick started"?

'Tain't so. Sounds plausible, until you think about it. If that
were so, how would the sap reach the top of a 50' tree? Even a
vacuum will raise water only 30'.

That explanation was proposed and debunked by early in the 19th
century - but, like all myths, cannot be killed by mere disproof.


Regards,
Nick Maclaren.



Interesting post on this at another forum:
http://www.city-data.com/forum/garde...ap-rising.html

pk

Very interesting PK, does not answer my question though. OK Nick if that
theory is wrong what is the actual answer as to how sap gets up the tree?