When the fall season arrives in temperate climates, deciduous trees undergo an amazing transformation of color in their leaves before they are shed for the winter. The varying hues of reds, oranges, yellows, and browns that emerge are a sight to behold for many. But what determines the particular colors that different tree species display in autumn? There are several factors that influence the pigments revealed as chlorophyll breaks down in the leaves.
The Science Behind Fall Foliage Colors
Leaves appear green during the spring and summer due to the abundance of chlorophyll, the pigment responsible for photosynthesis. Come autumn, as daylight hours shorten, chlorophyll starts to slowly break down, allowing other chemical compounds in the leaves called carotenoids and anthocyanins to show through.
Carotenoids are present in leaves year-round, but their yellow, orange, and brown colors are usually masked by green chlorophyll. As chlorophyll diminishes in the fall, these warm hues begin to emerge. Reddish-purple anthocyanins are also produced in leaves ahead of them falling, but only under certain conditions.
Cooler nighttime temperatures stimulate the production of anthocyanins. These pigments act as a sort of natural sunscreen for leaves, protecting the cells from damage as photosynthesis shuts down. The more sugar trapped in leaves due to bright, cool days and chilly nights, the more anthocyanins produced and the redder the foliage becomes.
Factors That Determine Leaf Color
Many complex variables influence the synthesis of carotenoids and anthocyanins in leaves and thus the autumn colors we admire. These include:
Tree species – The genetics of a tree determine the types and amounts of pigments present in its leaves. For example, some oaks turn brilliant reds while others take on russet browns. Maples are prized for their vivid crimsons, oranges, and yellows.
Weather conditions – Sunny fall days with cool, but not freezing nights spur the brightest leaf colors. Early frost can damage leaves and dull their colors. Excess summer rainfall causes less intense fall hues. Drought conditions often result in quicker leaf drop.
Soil composition – Leaves of trees growing in acidic soils tend to turn vibrant reds. Trees in more alkaline soils take on murky browns and tans.
Leaf position – Leaves at the tops of trees tend to color sooner and turn brighter colors than those in the shaded lower canopy.
Let’s take a more in-depth look at some of the most popular deciduous trees grown across North America and the leaf colors they are known for.
Maples
Maples are arguably the poster children for amazing fall color. Varieties such as sugar, red, and silver maples erupt into brilliant shades of yellow, orange, and blazing reds. The natural pigments they produce are why they are such a popular choice for landscape plantings.
Red maples get their name from the striking scarlet colors their foliage turns. The leaves can display every hue of red imaginable, from bright cherry to deep burgundy. Yellow and orange tints often blend in for added beauty. Red maples thrive in wet conditions, so are found along streams and swamps in eastern North America.
Sugar maples and silver maples turn more golden yellow, burnt orange and bronzy-red in autumn. The leaf shape differs too, with sugar maple leaves having distinct lobes while silver maple leaves have deep cuts between lobes, giving them an almost skeletal look. Both grow best in evenly moist, well-drained soils.
Oaks
Oak trees are prized for their immense size, longevity, and majestic crowns. They put on quite a show of color come fall too. Different oak species produce their own unique mix of leaf colors when cold weather arrives.
Northern red oaks are a standout with their rich, russet-red foliage. Pin oaks also flare brilliant scarlet. White oaks and swamp white oaks turn deep purplish-red. Chestnut oaks take on vibrant yellow with some orange mixed in. Black oaks go from green to lovely bronzy-brown. Bur oaks turn a muted tan-brown.
Most oaks prefer slightly acidic soil conditions. Red oaks flourish in well-drained sites while white oaks tolerate occasional wet feet better. Planting both types ensures fiery fall color since they peak at different times.
Aspens
Quaking aspen and bigtooth aspen are two spectacular trees that light up mountain landscapes each autumn. Their small rounded leaves quiver in the gentlest breeze, showing off their fall dress.
Quaking aspen is the most widely distributed tree species in North America. It grows in groves formed from one large interconnected root system. In fall, those groves erupt into shimmering hues of golden yellows and oranges, along with some radiant reds mixed in.
Bigtooth aspen inhabits higher elevations out West. It turns a stunning gold color that seems to glow against evergreen backgrounds. Aspens need ample moisture and love cool air. They thrive at high altitudes and latitudes.
Sweetgum
Sweetgum trees are a fantastic choice for warm southern climates. The five-pointed star shaped leaves turn on a kaleidoscope of fall colors – yellows, reds, purples, and oranges swirl together in an electrifying display.
Sweetgum is famous for the spiky seed pods it produces that litter the ground when they fall. But in autumn most eyes look up to admire the intense leaf colors this native southeastern U.S. tree achieves. It grows well on moist sites with acidic soil.
Dogwoods
The flowering dogwood is a treasured small ornamental tree known for its gorgeous spring blooms. But it brings dynamic color in autumn too with leaves that shift from deep maroon-red to vivid crimsons and rich purples.
Other dogwood species like kousa dogwood and Cornelian cherry dogwood also produce an impressive fall show. Their leaves transform to shades of red and burgundy before they drop.
Dogwoods thrive in part shade and prefer rich, well-drained, acidic soil. They are found growing wild across much of eastern North America. People love planting them as specimen trees for year-round beauty.
Smokebush
Smokebush sumac is an underutilized native shrub that delivers incredible fall interest. Its rounded leaves turn vibrant red and purple tones, looking like colorful puffs of smoke hovering around the branches.
There are both smooth and cutleaf cultivars. The fine-textured dissected leaves of cutleaf varieties seem to glow when backlit by the autumn sun. Plant smokebush in full sun and provide moderate water for the most intense leaf colors.
Sourwood
Also called sorrel tree, the sourwood displays incredible fall color. It is sometimes referred to as the Redleaf American lily-of-the-valley tree for good reason. Sourwood foliage transforms to fiery red and orange shades with hints of purple and yellow thrown in.
This slow-growing understory tree occurs naturally in southeastern mountain forests. It thrives in acidic, well-drained soil and part shade. Sourwood deserves greater use in landscapes to show off its spectacular autumn display.
Black Gum
Black gum or tupelo is native to wet woods and bottomlands of eastern North America. It is one of the first trees to start turning color in fall, showing off brilliant scarlet leaves accented with patches of bright yellow and deep purple.
No two black gums color up exactly alike. This adds to the visual impact when planted en masse. As a bonus, black gum grows into a pyramidal form that shows off its foliage to full effect. It adapts readily to varying soil types and pH.
Virginia Creeper
Virginia creeper is a fast-growing deciduous vine that can be grown on columns, fences, and arbors to add fall interest. Its palm-shaped leaves turn bright crimson before falling off to reveal grayish-brown bark with white veins underneath.
This versatile native vine grows 30 to 50 feet and cling to surfaces by holdfasts. It does well in full sun to part shade and tolerates poor soil, drought, pollution, heat, and wind. Virginia creeper makes a gorgeous red accent draping over other fading plants in autumn.
| Tree | Fall Leaf Colors |
|---|---|
| Red Maple | Scarlet red, orange, yellow |
| Sugar Maple | Orange, red, yellow |
| Silver Maple | Red, orange, yellow |
| Red Oak | Russet, red |
| White Oak | Purplish red |
| Pin Oak | Scarlet |
| Chestnut Oak | Yellow, orange |
| Black Oak | Bronzy brown |
| Bur Oak | Brown |
| Quaking Aspen | Golden yellow, orange, red |
| Bigtooth Aspen | Golden yellow |
| Sweetgum | Yellow, red, purple, orange |
| Flowering Dogwood | Crimson, purple, maroon |
| Smokebush | Red, purple |
| Sourwood | Red, orange, purple, yellow |
| Black Gum | Scarlet, yellow, purple |
| Virginia Creeper | Crimson |
Timing of Fall Foliage
Different tree species reach their peak fall color at different times based on variations in their leaf pigments. Tracking these progression can help you plan to see the range of autumn hues. Here is a general guide from earliest to latest:
Early: Black gum, sourwood, dogwoods, Virginia creeper, sumacs
Mid: Red and sugar maple, aspens, sweetgum, tulip poplar, black oak, hickories
Late: Scarlet oak, white oak, chestnut oak, beech, hawthorn
Remember leaf color changes with weather conditions too. Ideal conditions make for the most vibrant fall displays. Tracking foliage forecasts for your area helps time viewing around peak color.
Conclusion
The exceptional colors that leaves display each fall bring joy to many. With so many species of deciduous trees turning such a wide spectrum of yellows, golds, oranges, reds and purples, there is an abundance of eye-catching beauty to take in.
Understanding what influences the pigments produced in leaves adds appreciation for Mother Nature’s artistry. Take time to get out and observe the annual fall show near you. Note the range of hues different trees display season to season. Discover new favorites to add visual interest to your landscape.
Autumn leaf color is a fleeting phenomenon. Leaves reach their peak vibrancy for just days or weeks before dropping off. The interplay of cool weather, sunlight, and leaf chemistry creates a magical display. So bundle up, grab a warm drink, and soak in the amazing fall foliage while you can.
