• ES Picture of the Day 08 2020

    From Black Panther@21:1/186 to All on Tue Dec 8 11:00:40 2020
    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?

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

    https://epod.usra.edu

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