What do you see when you look at a patch of flowers?
Yellow Oxeye Daisy — they all look the same, right?
Maybe not — let’s take a closer look.
The central (cone) portion of these daisies (Rudbeckia species) are distinctly different in shape, with yellow tips emerging from different places in the cone.
Sunflowers, coneflowers and other members of the Compositae (or Asteraceae) plant family actually have two types of flowers on their floral structure. The colorful petals are sterile ray flowers (produce no sexual structures) designed to attract insect pollinators, while the tiny yellow projections from the central cone are the disk flowers that project first male (pollen), and then female (ovary) sexual structures. When fertilized, each ovary houses developing seeds, which cause the central cone to swell in size and in height.
A newly emerged flower has an almost flat profile, with a central disk that shows no projecting disk florets at all.
Later, a single row of disk florets emerges, and then fades after a couple of days, giving way to the next inner row of developing disk florets.
A cone is starting to form on this older flower, as the last rows of central disk florets emerges.
The seed head is almost fully formed here, and eventually the aging flower will drop its rays (petals), so that just the cone of developing seeds remains.
And so ends the lifespan of the flower…
Leaving a tightly packed seed head, ready to be harvested by hungry seed-eaters.
Back Yard Biology 