 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.


 Hygroscopic Pinecones

   December 08, 2020

    Humidity gradients11111111111

    Humidity gradients22222222

   Photographer:  Menashe Davidson
   Summary Author:  Menashe Davidson

   Recently, my curiosity was triggered when I read about the ability of a
    pinecone to open its woody scales in a dry environment and close
   them again when the humidity in the air is high. Luckily,  Yaar
   HaMeginim (Defender's Forest) is only a 20-minute drive from my home
   and is filled with  Jerusalem pines. There were plenty of  cones
   (top) scattered about after a long dry summer so I gathered up several
   dozen and took them home for an experiment. The open, dry cones were
   dipped in water (bottom photo, left). After an hour, (bottom, right)
   they’d closed.

   As the cones aren’t alive, this movement doesn’t use any internal
   energy. The trick lies in the nature of  the cone’s scales, which
   consist of two different microscopic tissues that have different
   affinities for water (they’re  hygroscopic). This allows the cones
   to close when atmospheric conditions become humid and to  open up
   when conditions are arid.
     * Yaar HaMeginim Forest, Israel Coordinates:  31.85226, 34.94425

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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.

https://epod.usra.edu
 
