"Sgt Pepper" wrote in message
...
I live in France in the countryside and see miles of sunflowers every year
and I have also noticed that they no longer follow the sun. It seems that
they all face east - to where the sun rises. I wonder if it's the EU who
have restricted the varieties and the only one they use now does not tourne
vers le soleil?

Roy

"Mike" wrote in message
...
On Thu, 24 Sep 2009 17:16:00 +0100, Sacha wrote:

On 2009-09-24 16:45:12 +0100, Mike said:

snip

Tournesol. And it could be the light reflection or it could be the
strength of the sun. ;-)) In fact, could it be because they're
starting to 'go over' now? Is the whatever-it-is that makes them turn
to the sun still active as the days shorten?

Perhaps .. like us with old age, they just stiffen up and lose
flexibility ?

Mike P


Extract from Wikipedia:

Sunflowers in the bud stage exhibit heliotropism. At sunrise, the faces of
most sunflowers are turned towards the east. Over the course of the day,
they follow the sun from east to west, while at night they return to an
eastward orientation. This motion is performed by motor cells in the
pulvinus, a flexible segment of the stem just below the bud. As the bud
stage ends, the stem stiffens and the blooming stage is reached.
Sunflowers in their blooming stage lose their heliotropic capacity. The stem
becomes "frozen", typically in an eastward orientation. The stem and leaves
lose their green color.
The wild sunflower typically does not turn toward the sun; its flowering
heads may face many directions when mature. However, the leaves typically
exhibit some heliotropism.
R.