Moonshine Ink Article --Fall 2003

At this time of year my garden (which no one notices in summer), comes alive with fall color. When I moved to California from Michigan, I decided to create a garden that would remind me of home in September and October, when I would have time to enjoy it.

My collection of shrub maples start turning orange-red in mid-September. The canyon or big tooth maples start first, one branch at a time. They are closely followed by the red, flame or amur maples. Tartarian, paper bark and vine maples turn later to various shades of red and orange. Hedge maples with their intense yellow foliage are the last to turn in my yard.

Adding to my color display are the yellow and sometimes maroon of my native birches which I raised from seed selecting for fall color in the wild. I also have aspen, dogwoods, chokecherries, spirea, Ribes species and Geranium sanguinium. My mountain ash collection is last to turn orange red in later October.

We are often asked what causes leaves to change color in autumn. Here is a brief discussion of the biology of fall color change by Eric Larusson.

Chlorophyll (green) is the main pigment in plants responsible for photosynthesis (the creation of plant foods with the energy from light). As days shorten, nights cool and plants dry, photosynthesis decreases an spent chlorophyll is not replaced. As the green of chlorophyll fades, other pigments which were previously masked begin to show. Carotenoides, tannins and anthocyanins are oher pigments also found in deciduous leaves. All leaves contain carotenoides which are important in transferring light energy to chlorophyll. Carotenoides are responsible for the golden yellow of Aspen, Norway maple and birch. Tannin is also contained in all leaves in varying amounts. When chlorophyll and carotenoides are gone and the leaf turns brown, tannin is responsible. Tannin gives us the the beige, tan and brown of autumn. Some trees such as Bur Oak have high concentrations of tannin and their leaves will only turn brown. Anthocyanins are present in many plants with red flowers, stems and with red fall colors. Anthocyanins yield colors ranging from pink to deep purple. Usually more light gives deeper colors. Rocky Mountain big-tooth maple and red-twig dogwood both grow in moderate to deep shade however, and both give intense red to purple fall colors. It is said that a more acid soil makes redder leaves and a more alkaline soil makes more purplish leaves. Drier conditions slow the production of chlorophyll and hasten the coloring. Orange leaves are a combination or anthocyanins and carotenoides.

Weather plays the most important role in determining the intensity of fall color in wild plants. Ideal conditions are warm sunny autumn days and cool (not quite freezing) nights. Without hard frosts some photosynthesis can continue to produce sugars which are used to make anthocyanins. Hard frosts will turn the leaves brown and cloudy, rainy days inhibit the color because of the lack of light and warmth. A few frosts early on will get the ball rolling.

Fall color to us also includes flowers, fruits and berries. Fall asters are still in bloom in early October along with Rudbeckias, tall Sedums, catmints, oreganos, salvia, scabiosa, golden clematis, Lychnis and tall Phlox. Fall booming crocus (Colchicum) begin peaking out of the ground with a display of fuschia blossoms on leafless stalks.

Mountain ash fruits in shades of orange and red are easily noticed in October along with the dark fruits of chokecherries, chokeberries crabapples, hawthornes and red, cranberry Viburnums.

In downtown Truckee , it is worth a walk to view the color at close hand. At Bank of the West (planted in 1980) look for mountain ash, paper birch, dwarf purple willow, hawthorne and crabapples. In the Post Office landscaping, (1984), featured are four different maples, crabapples, serviceberry, ninebark, currant, dogwood and sumac. The Eaton houses (1983) feature the largest , Big tooth maples in town along with some nice mountain ash. At the White house look for the red oaks and just east at a residence, the cranberry Viburnums.

My partners Rob Van Dyke, Eric Laursson, and I invite you to join us on our fall color walk through downtown Truckee which will begin at the nursery Saturday October 4 th at 10 and last until about 11:30.

is a botanist with Villager Nursery, Truckee.