It is September, the days are getting shorter, the weather
cooler. Plants put up a display that rivals or even surpasses that of spring.
Asters, goldenrods, coneflowers and a number of other similar flowers create a
golden explosion in gardens and meadows. Pollinators seem busier than ever,
taking advantage of this bounty. Insect flower visitors love yellow and flowers
seem to know it. They dress up in colors that attract their favorite visitors
in the hope that they carry pollen to other flowers of the same kind.
Pollinators, in turn, know that abundant resources await them in the bright
yellow flowers.
Let us look at one of these flowers in closer detail. Helenium, also called sneezeweed, has
the same structure as sunflowers and asters, a crown of petals and a center
made of little knobby structures called florets. Each one of those knobs is an
entire flower which produces pollen and seeds. Each one needs to be pollinated
in order to produce a seed. The dead heads you see later in the fall are little
packages of these nutritious mature seeds that bring joy to passing hungry birds.
The florets do not mature all at once. They proceed in an
organized fashion from the outer ring to the center, row by row; they open and
expose the pollen-carrying anthers and the pistils ready to receive pollen.
They also fill up with nectar. Only one row or two at a time are ready to
welcome visitors and to be pollinated. Bees know that. Even syrphid flies know
that. You can see them moving from floret to floret until they complete the
circle. Then they fly to the next blossom. They know enough not to waste time
on the unopened flowers or the ones past their prime.
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| Bumble bee collecting pollen and nectar from open florets. © Beatriz Moisset |
Take a look at figure 1. The sneezeweed blossom near the
center is quite fresh; most florets are still closed; only one is almost ready
for pollination. The one in the upper right is halfway through; there are still
some rows of unopened florets to go. The one below it is approaching old age,
almost all done. Now, you can look at Helenium
flowers and determine their approximate age just by looking at them. What do
you think about the flowers in figure 2?
Smart pollinators,
not only know where the food is in each flower, but also know that they will
continue to find supplies in the following days. Bumble bees are known to
faithfully come back to their favorite flower patches.
Sunflowers and asters do the same. See the following
examples:
List of articles
Beginners
Guide to Pollinators and Other Flower Visitors
© Beatriz Moisset. 2014
