What color are leaves? Green? The green in leaves is chlorophyll, a pigment plants use to collect energy from sunlight. The plants use this energy to extract water and minerals from their roots. The water and minerals, or sap, when combined with carbon dioxide in the air, produce sugars for the plant to feed on. This process is called photosynthesis.

During photosynthesis, deciduous trees (trees that shed leaves in autumn/winter) produce and give off oxygen and water. Some trees release as much as 150 gallons of water a day in the summer. That is why a deciduous forest feels so humid on a hot day! Meanwhile, a conifer forest feels less humid because their needles have a waxy-like surface that reduces the release of water.

As autumn approaches, there is less and less sunlight for trees to use to produce energy for photosynthesis. Also, the water in the ground may be less accessible, or even frozen, reducing yet another ingredient needed by the plant to produce food. A deciduous tree can no longer afford to lose water through its leaves.

To conserve food and water, a deciduous tree stops the flow of sap to the leaves. This causes the chlorophyll to fade, and reveals the yellow, orange or brown in a leaf, that had been earlier masked by the green chlorophyll. Red and purple appear when the sugars produced by the leaf begin to break down. Sunlight plays a role in this process. The brighter the days, the more brilliant the reds and purples produced.

While the fall foliage of some species is usually associated with specific colors; others species are known for producing a variety of shades on a single tree. (Note: Extreme soil and weather conditions can affect a tree’s fall foliage.)

Which colors are the trees listed here most likely to turn in the fall? Choices: yellow/orange, orange/red, red/purple, multiple shades.

1. American Beech

2. American Hop-Hornbeam

3. American Hornbeam

4. American Mountain Ash

5. American Sweetgum

6. Black Ash

7. Black Cherry

8. Black Oak

9. Black Tupelo

10. Box Elder

11. Common Hackberry

12. Common Persimmon

13. Common Sassafras

14. Downy Serviceberry

15. Eastern Black Walnut

16. Eastern Cottonwood

17. Flowering Dogwood

18. Gray Birch

19. Green Ash

20. Mockernut Hickory

21. Paper Birch

22. Pignut Hickory

23. Quaking Aspen

24. Shadblow Serviceberry

25. Shagbark Hickory

26. Silver Maple

27. Smooth Serviceberry

28. Sugar Maple

29. Sweet Birch

30. White Ash

31. White Mulberry

32. White Oak

ANSWERS

Yellow/Orange: 1, 2, 6, 10, 11, 12, 15, 16, 18, 21, 22, 23, 25, 29, 31

Orange/Red: 4, 8, 9, 13, 24, 27

Red/Purple: 17, 32

Multiple Shades: 3, 5, 7, 14, 19, 20, 26, 28, 30