Saturday, October 10, 2009


Katsura (Ceridiphyllum japonicum) in front of Japanese maple (Acer palmatum).

The trees native to this island (shore pine and paper birch, red alder, a few Douglas fir, Sitka spruce, western red cedar and willow) are not known for their fall colour. But a suburb is like an etch-a-sketch. Shake it up, make it blank, and start again. Plant things that turn colour, things from Asia such as the Katsura, which turns yellow then hazard-orange, or Japanese maple, which reddens nicely.

A more subtle pinky-red is provided by this Asian dogwood, Cornus somethingorother.

And an addition from eastern North America--staghorn sumac, a sprawly shrub that gradually morphs to a spectacular crimson.

It's all about anthocyanins (when it comes to redness --yellows come from a different pigment). Turned blueberry leaves (in this case, highbush blueberry, Vaccinium corymbosum, also not native) are anthocyanin-rich. The reds and purples arise as air temperature declines, chlorophyll production tapers off (a result of the chill, in part), and relatively high levels of sugar remaining in the leaves react with proteins in the presence of sunlight. Long series of sunny days and cool nights produce the most striking colours.

Different varieties of blueberry turn different degrees of red. This can be seen within commercial blueberry fields where multiple varieties are grown side by side.

Direct sunlight is necessary. Where a leaf lies atop another, anthocyanin tan lines will result.

To sum up, plant foreign things that produce anthocyanins in the fall if you like red leaves. Or, move somewhere where such plants naturally occur.

P.S. A very good description of the physiological/biochemical bases of leaf-turning is this source.


Wilma said...

Love the "tan lines" comment and photo. Nice post.

azplantlady said...

Who knew that there were so many different shades of red in nature? Thank you for sharing.

Karen said...

Oh, this explains the "tan lines" thing I saw on someone else's blog with hydrangea petals, I bet? Cool. I put in evergreen blueberries last year but may need to find some room for the leaf-turners. They are spectacular!

Eskarina said...

Wow, cool!
growing up in Ontario fall was always my favourite season because of the outstanding colours in all the maples and oaks (and sumacs).
I never before know why some went red and others yellow or orange.

Earl Cootie said...

Beautiful photos. And thanks for supplying that link. I've been thinking that I should do a tiny bit of research on the subject, but I've been too lazy to do anything about it. (You can't teach an old horse to read science unless you lead him to it.)

spinyurchin said...

Have you ever smelled Katsura trees when they are changing to yellow? Especially when they are warmed by the sun; they smell like caramalized cotton candy. Yum.

...unless it is just me and I have an embolism I don't know about.