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Emery Davis[_2_] · 04-02-2009, 05:48 PM posted to uk.rec.gardening

Charlie Pridham wrote:
In article , lid
says...
Charlie Pridham wrote:
In article , lid
says...
Not really a gardening question, but looking at some mistletoe in local
gardens made me think. It is an evergreen, but in the UK uses deciduous
trees/shrubs as a host. I wondered how it survives when the host is
dormant for so long. It is said that evergreen trees and shrubs can
survive cold weather very well providing their roots are not frozen.
But mistletoe must have frozen "roots" if the host branch is frozen, so
how does it deal with that situation?

Or have I got that completely wrong?

Many cold climate plants are quite able to be completely frozen solid
roots and all
That's the puzzle.

A cold-climate plant can "choose" to be either frozen and survive, or have
some sort of anti-freeze which might allow some movement of nutrients/fluid
around it and survive. If the host plant is frozen solid, what is the point
in mistletoe having anti-freeze if it cannot make use of the host plant's
fluids/minerals? I assume that mistletoe keeps its leaves in winter so it
can use them for photosynthesis. But it can't photosynthesize for long
without water - which it has to obtain from the host! So why is it
evergreen and not deciduous?

I don't know the complete answer but trees will start their sap rising
long before any leaves unfurl so there would be some advantage in already
having its leaves, water can also be absorbed directly along with
nutrients through leaves (hence folia feeding) so in winter it may not be
entirely dependant on the host plants sap

Yes, certainly in terms of the Norway Maple Pam mentioned. The sap
would already have been rising last month.

In fact this year I did some late maple pruning around Christmas,
thinking that the colder weather would have slowed things down. A big
mistake! A medium-small branch on A. cappidocicum ssp sinense (A.
sinense) bled and bled for weeks, through the deep freeze the sap
expanded and cracked the cambium below the cut down for several inches.
I really hope I haven't damaged it permanently...

-E