"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