 EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


 Bald Cypress Trees and Their Enigmatic “knees”

   May 07, 2021

    PattiW_DSC08923 (003)

    PattiW_DSC08930 2 (002)

   Photographer:  Patti Weeks

   Summary Author:  Patti Weeks

   The  Bald Cypress tree ( Taxodium distichum), native to the
   southeastern United States, thrives in the humid climates of the
   eastern coastal plain from  Delaware, down through Florida, over to
   eastern Texas and up the Mississippi River to southern Illinois. It’s a
   long-lived,  water-loving symbol of the swamp that grows to typical
   heights of 35–120 feet (10–40 m), with average trunk diameters of 3–6
   feet (0.9–1.8 m). However, records list the tallest cypress tree in
    Virginia at 145 feet (44.11 m), the stoutest in Texas at 39 feet
   (~12 m) and the oldest living tree in southeastern  North Carolina
   at 2,264 years old. As a testament to their longevity, an
    underwater bald cypress forest was discovered in 2012 several miles
   off the coast of Mobile, Alabama, 60 feet below the surface of the Gulf
   of Mexico. Likely uncovered by Hurricane Katrina in 2005, the
   well-preserved forest contains trees that are about 52,000 years old
   and thus most likely lived in the early glacial interval of the last
   ice age.

   The trees pictured here, more average in dimensions, are seen in their
   normal water level in the Cypress-Gum Swamp area of the 324-acre
    River Park North, which is adjacent to the Tar River in
   east-central Greenville, North Carolina. The water level can rise
   several feet higher after a heavy rain along with the rise in the river
   level. (If you look closely, you can see the water level mark on the
   largest tree, made by the 500-year flood of the Tar River as a result
   of the 1999 Hurricane Floyd.)

   Peculiar growths of cypress trees in swamps are “ cypress knees”
   that grow vertically from their roots above the normal water level.
   Their actual function is unclear, but it’s speculated that they may
   provide oxygen to the roots (as a possible  pneumatophore), allow
   nutrient accumulation or that they add stability to the wide,
   buttressed bases of the trees in the soft, muddy soil. While the
   function of  cypress knees continues to be researched, the aeration
   theory seems to be the most popular.

   Photo Details: Top - SONY DSC-RX10 IV camera; 33.51 mm focal length;
   f/3.5; 1/640 second exposure; ISO 800. Bottom - Same except 90.45 mm
   focal length; f/4.


   River Park North, North Carolina Coordinates: 35.6280, -77.3598


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Plant Links

     *  Discover Life
     *  Tree Encyclopedia
     *  What are Phytoplankton?
     *  Encyclopedia of Life - What is a Plant?
     *  USDA Plants Database
     *  University of Texas Native Plant Database
     *  Plants in Motion
     *  What Tree is It?

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   Earth Science Picture of the Day is a service of the  Universities
   Space Research Association.

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