Sunday, March 29, 2009
Why Dogwood Flowers Catch the Eye
The dogwoods are out! Three decades ago we learned what that meant as only living in Atlanta can reveal. Now they are at it once again here in our home in North Carolina.
Of course the answer to the question includes dogwood's early appearance in spring before many other flowers are out and when few leaves have yet emerged. Spring sunlight filtered only by naked branches highlights both white and pink varieties of Cornus florida. Dogwoods filling the gap under a canopy of larger trees show the typical layered growth of a sub-canopy species, spreading branches horizontally so leaves capture the greatest amount of the limited supply of the sun's photons that penetrate deep into the forest. Before the leaves emerge, the showy flowers often mimic the green layering to follow, creating waves of white and pink.
But the dogwood's "flowers" consist of more plant parts than the typical flower. Those showy "petals" started out as four green bracts that enclosed an inflorescence, a bunch of the dogwood's tiny green flowers. As the bracts unfold they reveal 10 to 20 or more of C. florida's real flowers, the tiny green knobs collected at the center of the bracts. Each of these flowers will open, and small insects will spread pollen from the four anthers of each flower to the pistil of other flowers. The resulting fertilization of ovules will lead to the bright red berries each containing a single dogwood seed this fall. Each dogwood inflorescence can produce one to several berries.
The U.S. Forest Service maintains a page with all the botanical information you could ever want to know about dogwoods here:
Visit this interesting site for a complete photographic sequence of dogwood flowering and fruiting: