Saturday, September 26, 2009

The Life of a Flower

© Beatriz Moisset
Let us take a simple flower, the simplest you can think of, the one you drew when in Kindergarten. A yellow circle surrounded by petals. It looks like a daisy or a sunflower or an aster or a number of flowers with petals arranged like sun rays and a circle or disk at the center. Well, there is a surprise here; such a flower is far from simple. It has a very complex structure, in fact it isn't just a flower but a whole bunch of tiny flowers. Look at the little parts that comprise that yellow center. What a surprise! Each one looks like a tiny flower all by itself: five petals and a center with little things inside that resemble the center of many other flowers that you have observed at various times. Well, that is exactly what they are. Each one is a flower, called a floret; they are all clustered together.
Each floret contains all flower parts: petals, anthers, stigma
© Beatriz Moisset

You may wonder about the petals that surround this cluster of flowers. Here is the answer: there are two kinds of flowers in this interesting bouquet; only the ones that make the outside rim have petals, the large petals that we see. They are called ray flowers while the ones in the center are called disk flowers. It would be nice if all technical jargon were as obvious as this.
In a newly opened sunflower or helenium, the disk flowers are just like little knobs. The next day the outer line of disk flowers has opened and you can see the sex parts, the pollen and seed producing parts, sticking out. Afterward, each day or so a new row of flowers open. The old ones begin to wilt; they look open and a little dry. Eventually one smaller circle after another opens and passes its prime.
Now let us observe the pollinators that come and visit the flower. They go directly to the freshly opened florets. They have nothing to do with the unopened ones, nor with the wilted ones. They find pollen and nectar only there and they know it. All this goes according to the plans of the flower; this works just right to ensure pollination.

© Beatriz Moisset
One interesting thing is to look at the older flowers that have completed their cycle. The ray petals stay fresh and bright for a few days longer although that flower is no good to pollinators any more and it doesn't need visitors either; right now it is busy growing the seeds that will mature later on.
You may wonder why it continues to look attractive to pollinators. The reason is that a large clump of flowers is more likely to attract pollinators that are passing by than a smaller clump, with many dry blossoms in between. It is like you going shopping; a mall where many stores are closed or vacant is likely to drive you away rather than attract you. Once there, you aim for the store that interests you. Pollinators do the same; they notice the larger displays of flowers than the smaller ones, with the certainty that they will find some food there.
Helenium. The flower on the left is young, only a few florets opened
The one at right is older, most florets are past their prime
© Beatriz Moisset
Such flowers are skilled engineers, and good marketers. They know their clients and how to satisfy their demands, and they get good returns. Other flowers are arranged differently; they use different attractants; their timing varies; but they all know how to maintain a successful partnership with their pollinators.
The clients, on the other hand, know how to use this resource. You can see a bee visiting methodically all the florets and probing them with its long articulated tongue in this video

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© Beatriz Moisset. 2010

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