Reviewed June 1998

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Autumn Colors

Leaf mapJulie L. Rhoads
School of Natural Resources

The spectacular parade of colors associated with the "Indian Summer" days of autumn is created by a complicated series of interactions involving pigments, sunlight, moisture, chemicals, hormones, temperature, length of daylight, growing location and genetic traits. A precise clockwork within the leaf cells sets the forests of Missouri ablaze when early fall days are bright and cool, and nights are chilly but not freezing.

Several central Missouri highways have reputations for being particularly beautiful autumn drives:

  • Highway 19 between I-70 and Hermann
  • Highway 94 north of the Missouri River between Jefferson City and Hermann,
  • Highway 100 south of the Missouri River between Hermann and Washington.

Rob Hill photo


 

A favorite route for fall foliage watching in eastern Missouri is Highway 79 along the Mississippi River between Winfield and Hannibal.

Good colors can also be found on the bluffs along the Missouri River Trail in the central part of the state around Columbia and the Piedmont area around Ironton.

The leaves of the growing season are green because of the formation of chlorophyll, a pigment found in minute leaf structures called plastids. Chlorophyll is the change agent for food making in green plants. These green pigments use energy from sunlight, carbon dioxide from air, and water from the tree itself to produce simple sugars that feed the tree in a delicate process known as photosynthesis.

Rob Hill photoYellow and orange pigments called "carotenoids" are also present in the leaves during the warm weather of the growing season, but are "masked" by the greater amounts of the green pigments. Autumn's dropping temperatures and decreasing daylength stop the production of new green pigments and cause existing chlorophyll to degrade at an accelerated rate. The yellow pigments are then "unmasked" as the green pigments disappear, accounting for the brilliant coloration of Missouri hardwood species such as hickories, birches, cottonwood, sassafras, poplars and hackberry.

These autumn environmental stimuli also cause the leaves to form a hormone called "abscisic acid." The abscisic acid induces the plant to form weak layers of new cells at the base of the leaf stem. These "abscission zones" eventually break apart from wind or other physical disturbances, often causing the leaf to fall before the yellow and red pigments have deteriorated.

Rob Hill photoThe pigments responsible for the vivid red and purple autumn colors of persimmons, dogwoods, maples, sumacs, sweetgums and ashes come from another group of cell pigments called "anthocyanins." Anthocyanins develop in the sap of leaf cells in late summer and are stimulated by lowering temperatures and high light levels. If the tree's sap is acidic, the leaves become red; alkaline sap causes purple coloration. Anthocyanin formation in the leaf depends on a simultaneous increase of sugars in the presence of bright light and a decreasing level of phosphate caused by the chemical moving out of the leaf into the stem. Mild drought conditions also stimulate production of the red pigments.

Carotenoids and anthocyanins often combine in leaves to give the deep oranges, fiery reds, and bronzes typical of many hardwood species. Brown autumn leaf color of oaks and beech is due to the presence of the brownish tannin compounds in combination with the carotenoids.

Several environmental factors can diminish the fall foliage colors. Very warm weather conditions encourage late season chlorophyll production and vegetative growth, which discourages initiation of autumn colors. An early frost before abscission kills the leaf before the pigments reach their maximum development, causing it to simply shrivel and fall to the ground. Long periods of wet, cloudy weather in fall produce a drab coloration because of low light intensity.

To summarize, cool but not freezing temperatures, mild late-season drought and sunny days are necessary ingredients for creating the brightest fall colors of the Missouri woodlands.

Rob Hill photo

Fall colors for common native Missouri deciduous trees

  • Ash, green
    Fraxinus pennsylvanica
    Yellow
  • Ash, white
    Fraxinus americana
    Orange/purple
  • Basswood, American
    Tilia americana
    Brown/yellow
  • Birch, river
    Betula nigra
    Yellow
  • Bladdernut, American
    Staphylea trifolice
    Yellow
  • Buckeye, Ohio
    Aesculus glabra
    Yellow
  • Cherry, black
    Prunus serotina
    Yellow
  • Dogwood
    Cornus florida
    Red/purple
  • Elm, American
    Ulmus americana
    Yellow
  • Hackberry
    Celtis occidentalis
    Yellow
  • Hawthorn, downy
    Crataegus mollis
    Red
  • Hazelnut
    Corylus americana
    Yellow
  • Hickory, bitternut
    Carya cordiformis
    Yellow
  • Hickory, shagbark
    Carya ovata
    Orange/yellow
  • Honeylocust
    Gleditsia triacanthas
    Yellow
  • Ironwood
    Ostrya virginiana
    Yellow/red
  • Maple, black
    Acer nigrum
    Yellow/orange
  • Maple, red
    Acer rubrum
    Yellow/orange/red
  • Maple, silver
    Acer saccharinum
    Yellow
  • Maple, sugar
    Acer saccharum
    Yellow/orange/red
  • Musclewood
    Carpinus caroliniana
    Yellow/orange/red
  • Oak, post
    Quercus stellata
    Brown/red
  • Oak, northern red
    Quercus rubra
    Red
  • Oak, white
    Quercus alba
    Brown/red
  • Persimmon
    Diospyros virginiana
    Orange/yellow/red
  • Poplar
    Populus deltoides
    Yellow
  • Redbud, eastern
    Cercis canadensis
    Yellow
  • Sassafras
    Sassafras albidum
    Orange/yellow/red/purple
  • Serviceberry, downy
    Amelanchier arborea
    Yellow/orange/red
  • Sumac, smooth
    Rhus glabra
    Red
  • Sycamore, American
    Platanus occidentalis
    Brown/yellow
  • Walnut, black
    Juglans nigra
    Yellow

G5010 Autumn Colors | University of Missouri Extension