I discovered that not only does the same tree have different colors different
years, as Archie & others pointed out, but climate & location play a part. Soil
pH was also mentioned.
I recently bought a pre-bonsai Acer palmatum 'Arakawa,' the rough-barked maple.
This cultivar, although otherwise a typical Japanese maple, is grown for its
rough, corky bark. The trunk & a few branches on mine are beginning to show
this trait. Vertrees, the #1 Japanese maple maven, lived in Oregon, & also
collected much of his information from a nursery in England. He reported that
'Arakawa' is yellow in the fall, & this is copied in Maples of the World.
In general, England & Oregon are not especially noted for fall leaf color.
Central NY and the Northeast US are. Well, let me tell you my 'Arakawa' (there
is no doubt of its identity) has turned a bright orange-red. A picture of it on
the Web shows fall color a dark red.
Even more interesting, Maples of the World goes into this subject further. In
this country, and most of western Europe, Norway maple, Acer platanoides, is
noted for having crappy fall color. The leaves turn an insipid yellow & fall
off. However, the book mentions that in Eastern Europe & the Caucasus, Acer
platanoides has beautiful fall color. Of course the next step would be for
someone to go out to those parts, dig up a few young specimens of Norway maple
with nice fall color, and plant them in the US to see what will happen.
Meanwhile, a Japanese maple that was plain green last year, & I was thinking of
getting rid of because of a root problem (not disease), turned mostly dark red
last week, so I will have to keep it.
My Amur maple turned the shade of red it is supposed to be.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra

Iris Cohen wrote:

I discovered that not only does the same tree have different colors different
years, as Archie & others pointed out, but climate & location play a part. Soil
pH was also mentioned..

This is also true in Texas for oaks. We're not known for our fall
color down here. Most of our oaks just turn paper-bag color and drop
their leaves, but one year in about 15, we have just the right
combination of warm days, cool nights, and perfect moisture and we see
russet and peach and gold. It's enough to make a botanist play hooky
to go out and enjoy. It does not look as if this is going to be such
a year...

M. Reed
College Station, TX

(Iris Cohen) wrote in
:


Well, let me tell you my 'Arakawa' (there is no doubt of its
identity) has turned a bright orange-red. A picture of it on the
Web shows fall color a dark red. Even more interesting, Maples of
the World goes into this subject further. In this country, and
most of western Europe, Norway maple, Acer platanoides, is noted
for having crappy fall color. The leaves turn an insipid yellow &
fall off. However, the book mentions that in Eastern Europe & the
Caucasus, Acer platanoides has beautiful fall color. Of course the
next step would be for someone to go out to those parts, dig up a
few young specimens of Norway maple with nice fall color, and
plant them in the US to see what will happen. Meanwhile, a
Japanese maple that was plain green last year, & I was thinking of
getting rid of because of a root problem (not disease), turned
mostly dark red last week, so I will have to keep it.
My Amur maple turned the shade of red it is supposed to be.

Remember that most of Europe is north of most of the US, so there is
a major daylength difference. There isn't any real evolutionary
pressure for a tree to be pretty in the fall, it is just something
that some of them do.

Sean

Remember that most of Europe is north of most of the US, so there is a major
daylength difference.

I don't think that accounts for it. New England is pretty close to the latitude
of much of Europe. I think the main difference is the Gulf Stream. The
northeast US has more extremes of temperature and weather than western Europe.
Eastern Europe & the Caucasus have a more severe climate. Foliage color is a
byproduct of sugar storage. There is evolutionary pressure for trees in a
severe climate to store more sugar for the winter, hence the fall color.
However, that does not explain why Acer platanoides in the northern US lacks
fall color, while the same species on the other side of the world in a similar
climate has nice colors. That's why I want someone to transplant those trees
from the Caucasus. Since Norway maple already has numerous traits which make it
popular, nice fall color would be an additional selling point. Look at the
popularity of 'Crimson King.' The only danger is that if they are attacked by
some new plague, the devastation would equal what we had from Dutch elm
disease.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra

Sean Houtman wrote:

There isn't any real evolutionary
pressure for a tree to be pretty in the fall, it is just something
that some of them do.


There are two major hypotheses to explain colorful fall leaves. One is
that red anthocyanins act as a sunscreen and act as antioxidants. The
other is that colorful leaves repel insects.


The Warm Hues of Fall Foliage Competing theories try to explain the
season's spectacular show of color, but most come up short:
http://www.sciam.com/article.cfm?art...75809EC5880105

A Puzzle for the Autumnal Equinox:
http://www.corante.com/loom/archives/015786.html

Why Leaves Turn Color in the Fall:
http://www.the-scientist.com/yr2001/...p8_011210.html



David R. Hershey

There are two major hypotheses to explain colorful fall leaves. One is that
red anthocyanins act as a sunscreen and act as antioxidants. The other is that
colorful leaves repel insects.

In that case the trees would have red leaves in midsummer, when there is more
sun and there are more insects.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra

(Iris Cohen) wrote in message ...
There are two major hypotheses to explain colorful fall leaves. One is that
red anthocyanins act as a sunscreen and act as antioxidants. The other is that
colorful leaves repel insects.

In that case the trees would have red leaves in midsummer, when there is more
sun and there are more insects.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra

The usual explanation of the sunscreen/antioxidant adaptive value of
anthocyanins is that the need for these is actually greater during the
combination of intense cold and bright sun that occurs in fall. This
is at least plausible because it is the combination of fine days and
intense, but not killing, cold that causes the best development of red
colors.

--
Chris Green

(David Hershey) wrote in
om:

Sean Houtman wrote:

There isn't any real evolutionary
pressure for a tree to be pretty in the fall, it is just
something that some of them do.


There are two major hypotheses to explain colorful fall leaves.
One is that red anthocyanins act as a sunscreen and act as
antioxidants. The other is that colorful leaves repel insects.


The Warm Hues of Fall Foliage Competing theories try to explain
the season's spectacular show of color, but most come up short:
http://www.sciam.com/article.cfm?art...F26-7ABD-1D94-
92758
09EC5880105

A Puzzle for the Autumnal Equinox:
http://www.corante.com/loom/archives/015786.html

Why Leaves Turn Color in the Fall:
http://www.the-scientist.com/yr2001/...p8_011210.html




Yes, I have no arguement with the usefulness of the pigments in the
leaves. If there was no advantage given, the plants would not expend
so much energy making the pigments. It is just that the pigments are
not there to make the leaves pretty in the fall, and the effect of
nice colors just before the leaves drop does not improve the chances
that the tree will reproduce.

Sean