Sunflower
Helianthus annuus
If you pick a sunflower, you're
actually picking hundreds of flowers. In the brown center of each
flowerhead are rows of unopened male and female flowers. When the
male flowers are ready to shed their pollen, they send up long threads,
called stamens, full of sticky pollen. Insects such as honey bees
and long-tongued flies brush up against the pollen before flying
off to another plant. This is how the pollen spreads to other flowers
to form seeds. Some sunflower pollen is also spread by wind. The
wind-borne pollen may contribute to late summer hay fever, but it
gets blamed for more than its fair share. The pollen is waxy and
has long sharp spines. Instead of catching the wind, it tends to
clump onto other pollen and drop. The sunflower is a true American
native. In late summer the cheery flowers line roadsides from Canada
to South America. These wild sunflowers are relatives of the gigantic
ones--with flowers the size of dinner plates--that farmers now plant
as a crop.
|