Thursday, September 18, 2014

Sneezeweed or Helenium

Halictid male bee on Helenium. © Beatriz Moisset
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.

Fig. 1. Three Helenium blossoms of different ages. © Beatriz Moisset
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.

Fig. 2. Several Helenium or sneezeweed flowers. © Beatriz Moisset
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.

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?

Another bumble bee. © Beatriz Moisset
 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:

Agapostemon female on sunflower. © Beatriz Moisset

Halictid bee on coneflower. © Beatriz Moisset

Syrphid fly, Toxomerus on daisy. © Beatriz Moisset
Skipper on sunflower. © Beatriz Moisset

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2014