|
| White Geranium (Aspen, Colorado) |
|
|
| click to view this & other larger images.... |
Have you ever looked closely at a flower to see all of its
different parts? Most of us probably have and I'd guess that almost everyone would recognize terms for flower parts
such as ovary, stamens, anthers, pollen, styles, pistil and petals. We might not be able to tell what role each of those
parts play but we generally know they have something to do with reproduction.
This isn't a botany lesson and I'm no botanist but a year or so ago
while attending a presentation about the sex life of flowers I learned something rather amazing about flowers and their reproductive
process. I want to briefly share that tidbit of knowledge with you and then invite you to look at some close-up photos
of geraniums to see a few examples of these wildflower sex organs in action.
Most wildflowers are hermaphrodites which simply
means they have both male and female reproductive parts. Did you ever wonder how a plant manages to avoid self-fertilization?
It has to do somewhat with timing and also with the plant's molecular chemistry which in some species prevent it from
being fertilized by its own pollen. My little discussion here is to talk about timing (kind of a type of rhythm
method for plants).
| Wild Geranium (immature) |
|
|
| Click photo to enlarge... |
When you look at the center of many flowers--like the geranium--the
central "stalk" you see is called the pistil. From bottom to top it includes the ovary, style and stigma. These are the female parts of the flower.
When properly fertilized the ovary produces seeds.
The little stalks all around the periphery of the central "pistil"
are the male parts of the flower and are called stamens. A geranium typically has 10 stamens. The stamen includes the filament and the anther. It is the anther
that is on the very tip of the stamen and this is where the pollen is produced. Some plants have very large anthers
and produce large grains of pollen while others are much smaller (remember guys, size doesn't matter).
| Close-up Showing the 5 Stigma Have Opened |
|
|
| Click to enlarge image.... |
The very tip of the female part of the flower, called the stigma,
has to "open" in order to receive pollen for feritilization. In many plants this doesn't happen until a few days after
the plant's male parts--the anthers--have started producing pollen. The result is that the plant is less likely
to self-pollinate. In my geranium photos you can see on many of the flowers that it is clear the 5 tiny stigma
on its center style aren't open. Those flowers cannot yet be pollinated--even though their male parts--the anthers--are
producing pollen. Look at the photos and you'll see some plants have their 5 stigma clearly on display and others seem
to just come to a single point at the tip of their style. The single pointy ones aren't yet open.
| Staggered Maturity for Stamens |
|
|
| click to view larger image... |
Geraniums also tend to have staggered maturation dates for their stamens
with anthers (these are the pollen producing parts). This enhances the chance that one plant's stamens & anthers
(the male parts) will be producing pollen at the same time when another geranium neighbor has an open stigma (the female
part). This improves chances for cross-pollination among neighboring plants.
I've probably botched the details of this process,
and I know I've generallized enough to have given a real botanist a stroke, but hopefully you'll get the ideas I'm trying
to convey and when you look at the photos I'm betting you'll have a new appreciation for the role each part of the flower
plays in the reproduction of that flower.
| Sticky Geranium--the title did mention "Sticky"... |
|
|
| Click to go to full picture gallery for geraniums... |
Puzzle solved! In my original post to this website I'd posed
the question as to why the Sticky Geranium (Geranium viscosissimum) pictured here has 6 stigma instead of 5.
The answer seems that it is just an illusion. The "6th" stigma is actually the supporting style (the stem) for
the stigma. It just looks like it has 6 stigma.
Click on the Sticky Geranium photo to open a new window where you'll see the photo gallery I've
posted for geraniums.
|
