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.


Following the Sun

October 16, 2020

Sunflower Field

Sunflowers facing east

Photographer: Kathy Arbuckle
Summary Author: Kathy Arbuckle

Late July and August is sunflower time in eastern Washington State.
Many farm fields are filled with the cheerful faces of huge, yellow
blooms facing east to greet the Sun each morning. Young sunflowers
have the ability to track and follow the Sun as it passes east to
west, displaying heliotropism, the diurnal movement of plants
in response to the direction of the Sun.
Researchers discovered that this is accomplished during the day by
the plant growing slightly more stem on its east-facing side to cause
the flower head to gradually face west, while at night it grows a
longer stem on the west-facing side to return the bud to facing east.
This cycle is repeated every 24 hours, according to the plant's
internal circadian clock.
Sunflowers stop this mechanism at maturity and from then on set the
blooming flowers facing east permanently, benefiting the plant's
ability to attract bees and other pollinators to their golden,
sun-warmed flowers. Photos taken on July 20, 2020.

Photo Details: Top - Camera NIKON COOLPIX P90; Software Nikon Transfer
1.3 W; Exposure Time 0.0040s (1/250); Aperture ƒ/5.6; ISO equivalent
64; Focal Length (35mm) 212. Bottom same except - Exposure Time 0.0027s
(1/366); Aperture ƒ/6.3; Focal Length (35mm) 37
* Spokane, Washington Coordinates: 47.6588, -117.4260

Related EPODs

Following the Sun Indian Pipe EPOD 20th - Diatom Wreath
EPOD 20th - Fence Eating Tree EPOD 20th - Giant Puffball
EPOD 20th - Driftwood at La Push, Washington
More...

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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