Recently after writing numerous articles on flowers, I came to realize how little I remembered of their anatomy. While the words stamen and anther floated off in the foggy parts of my brain, none of the public school science class came along for the ride, so as usual I decided it was research time again, knowing, there would be so much data my brain would swell!
Certainly I was not disappointed at what I found out, but never in my wildest dream did the anatomy of a plant, or pollination seem so exciting. Or perhaps I should call the article, the sex life of a single plant! Okay, laugh all you like, but I did come to learn about the male and female parts, the sperm cells and the ovule.
Unlike in humans, most of the time these parts are in the same plant, but occasionally there are plants that hold one sexual part, waiting for the opposite part of the same species. In neither case does conversation or interest play a role. Appearance on the other hand is almost everything, as the attraction of insects to a lovely looking bloom is the first stem in a complex cycle.
While each plant has many complex cycles, such as root, nutrition and cellular growth just to name a few, I am just exploring the role of the flower in ensuring the plant propagates. Not all plants flower or spread by seed, but those that do are the most common in our garden and are enjoyed by both people and insect populations. Surely the terminology of the anatomy of a flower and steps of plant sex are complicated, and so several diagrams will follow, as well as some photographs of lovely blooms.
Anatomy of a flower
A. Peduncle E. Petals
B. Ovary F. Anther
C. Style G. Stamens
D. Stigma H. Sepals
Each flower bud is attached and supported by a peduncle or in common terms, a stalk or stem( see A above). The stem gives support to the developing flower from the elements and insects so it is not destroyed before the seeds are formed. From this stem grows the Sepal ( H), which is a leaf like part that protects the maturing bud and supports the base of the flower once it is open.
Each boom is composed of petals which make it visually attractive and often pleasantly scented. While the number in each bloom varies, as do the styles and shapes, their purpose is the same . Despite any physical differences on the outside, their role is to attract insects in to the flower. Once there, the insects collect pollen on a body part, often the legs and transfer it when they go in to the bloom of another plant.
The Stamen is the male flower part and is composed of two parts:(F) Anther and (G) Filament.
There they go…the little honey bees, looking for nectar and moving pollen by landing on the Anther. Now the Anther, or male pollen producing reproductive organ of the flower, blows in the breeze high atop the Filament.
The Filament is a thin stem that provides support for the Anther making it easier to be seen and for visits by local insects. The Anther has two lobes, both of which have spore making sacks called Microsporangia. The micro spores inside split by mitosis, so both the nucleus and cytoplasm are identical …an exact duplicate of the parent plant in each grain of pollen. Once the pollen is mature the Anther then opens for transfer by wind, water or the general bug population.
Technically the male part of the reproduction equation here, in brief comes down to the Stamen is a tiny Filament with a bumpy two segmented Anther on top. The usually pale yellow pollen maturing there is then released to carry the plants genetic material, with each grain of pollen containing cells that eventually for sperm cells. Yes, that is what they are called and they do travel in search of the Ovary.
The Pistil is composed of single or multiple units that are separate or fused. Each unit is called a Carpel.
Each Carpel has four parts: the Stigma ( D)
Ovule (inside B)
The top of this section or the Stigma can be long and slender to feathery in appearance. In addition to receiving the pollen transferred by insects, the Stigma also rejects the pollen of other species preventing mutation. Once on a compatible Stigma, the sugary fluid formed there causes the pollen to germinate.
The Style is a tube-like portion between the Stigma and the Ovary that can be short or lengthy. Germinated pollen on the Stigma grows a pollen tube that carries the sperm cells by drilling its way through the nutrient rich Style carrying the sperm cells towards the Ovary. . In some cases the style is responsible for self-incompatibility, causing pollen tubes to fail.
The Ovary is the female reproductive organ of the flower and the part of the Pistil that hold s the Ovules. Once the pollen tube reaches here, the now grown sperm cells are delivered to the ovule.
In seed propagating plants, the ovule contains the female reproductive parts and consists for three parts. There is an outer layer, a nucleus and inside the nucleus is the actual egg cell which is the site of the fertilization. After one sperm achieves this, the ovule becomes a seed cell that forms other seed. The second sperm cell changes and grows to become the food supply for the embryo.
In addition, the plants have stores of starch, protein and oils as food for the developing embryo and developing seedling, similar to the yolk of animal eggs. There are also other terms and complex steps that are referred to in the same terms at human sexual reproduction, such a placenta, and umbilical cord.
I have spent quite some time sorting through the facts before writing this article and the only real conclusion I have is that describing the parts of a flower that are involved in its sexual reproduction, as complicated as trying to explain the development of a human baby.
Of course the other obvious part of this conclusion is that life is a miracle , no matter how many terms and books describe the science behind it.
Now I admire the lovely blooms of my garden and feel even more connected and inspired to share their enthusiasm…time to smell the roses!