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