Naturalist/Educator at the Cable Natural History Museum
As tree leaves stop gathering sunlight for food and prepare for the winter, it seems like that extra light is reflected back to our eyes in the brilliant colors of fall foliage. Green chlorophyll has faded away, and sugars it produced all summer are stored deep within the tree as starch.
In some trees, the fading chlorophyll reveals yellow and orange pigments. In other trees, red pigments are created in bright sunlight. While I appreciate the golden light that filters through an aspen stand in fall, it is the red leaves that make me really love autumn.
The staghorn sumacs around here are particularly colorful as their leaves morph through a rainbow of color, ending on crimson. They are also fast growing, short-lived, and tolerant of a wide variety of soil types and moisture levels. I am thrilled that sumacs like road ditches, because admiring their lively colors can improve almost any long drive. Sumacs are interesting beyond just their colors, too. Did you know that they are a member of the cashew family? This family also includes mangos, pistachios, and poison ivy!
Even while the leaves are still green, sumacs start to show red. Large conical clusters of red-furred fruits sit at the ends of branches, giving a good show of color from June-September. Not every clump of sumac produces fruits, though. This observation troubled me off and on for years, until I realized two important parts of sumac’s biology: it is dioecious, and it reproduces vegetatively by rhizomes. Let me explain…
Dioecious (which means “two households” in Greek) indicates that each individual plant has reproductive units that are either only male or only female. Most flowers you encounter are monoecious, which means they have male and female parts in the same flower (“one household”). For sumac, this means that some trees are only male, and do not produce fruit. Ah! That is one part of the equation.
Rhizomes are modified stems that creep underground and send out roots and shoots from their nodes. If you chop a rhizome up, a new plant could grow from each piece. Asparagus is a great example of a plant we propagate by its rhizome. In a clump of sumac, the rhizomes stay connected, and new plants grow outward from the center. Since the oldest, tallest plants are in the center, clumps of sumac are often attractively dome-shaped.
As the sumac grows new shoots from its rhizome, it is actually producing clones of itself. If the parent plant is male, all the offspring will be male, too, and that clump will not produce fruit. Mystery solved!
To reward yourself for this new knowledge or for a bit of refreshment as you enjoy the fall foliage, why don’t you make a pitcher of sumac lemonade? Gather a half-dozen berry clusters and steep them in a pitcher of cold water for an hour or so. Strain out the seeds, hairs, and bugs through a cheesecloth. Add sugar or maple syrup to taste (remembering that these sweeteners were made by plants using sunlight), then chill and enjoy the rewards of a summer well-lived!
For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.
Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/