Trying to Understand Angiosperms

Take a look at this small group of very small flowers from my Coleus blumei.

Today I’m going to try and explain a little bit about what makes flowering plants, or Angiosperms, so special in the plant world and some of the fascinating properties that go along with that.

Sadly this was the only plant that I have flowering right now and photographing everything properly is going to be a chore. First I guess I should explain a little bit about the four different typical flower organs and their functions. Most angiosperms consist of Sepals, Petals, Carpels and Stamens. Lets dissect a single flower to explore more of the inside.

(Before picture of Coleus blumei)

(After photo of a dissected Coleus blumei flower. The flowers organs are as follows from top to bottom left to right: Pollen Grains, Stamen with Anther and Filament, Petal, Carpel with Stigma, Style and Ovary connected to the Receptacle and the Sepal)

The Carpels and Stamens are the reproductive organs on the flower, the Carpel (Also called a megasporophyll) is the female portion and consists of a stigma, style and ovary. The male counterpart is the stamen and they consist of an anther and filament. Sometimes I like to remember things like “The females hit the stigma and got the style” the ovaries part should be obvious. Usually when flowers posses all four of these organs they are called complete flowers, inversely when one or more are missing they are called incomplete flowers. Today we are dealing with a complete flower. All of these flowering parts are attached to a receptacle that is attached to the sepals. To try and make is easier to understand the whole process I want to try and draw a picture.

I guess after looking at it a little later it also seems confusing. Process 1 and 2 are both haploid cells, they have a single set of unpaired chromosomes just like human sperm and egg cells. Once they finally meet at the bottom is when they turn into diploid cells, except in the case of the sperm cell that travels into the endosperm, that sperm cell becomes a triploid food supply for the baby seed. At that point the seed is encased with fruit. Fruit being; any fertilized flower in a mature ovum. The process is known as double fertilization.

(This is a single seed on a U.S. penny)

This is what it was all for, a seed rich in genetic diversity, ready to survive the elements, and the test of time. Did you know that we have no idea how long seeds can stay alive for if properly stored? At first people were keeping many different seeds stored and checking on them every ten years. Sounds like a pain in the ass, yes? Luckily in 2005 a Judean Date Palm seed was successfully germinated after 2000 years being dormant, ending that boring science experiment mentioned earlier. THEN in 2012 some goober had to tried to plant some 32,000 year old iris seeds that were hidden by some chipmunk punk somewhere in Siberia, guess what? They actually germinated too. So right now it seems like there is no known expiration date as long as you keep the seeds in a stable environment. Amazing right?

My baby Coleus seedlings

So here is the coleus seedlings after about two weeks. you can see they all they their cotyledon leaves still, those are also called “Seed Leaves” they are protective leaves that reside inside of the seed, you can even see them in my drawing from earlier at the end in the mature seed.

(Seedling next to seed)

I removed one of the seedlings so we can observe the Taproot and the Cotyledons. The first and largest root that grows out of the seed is refereed to as the Radicle. Don’t worry, no seedlings were harmed in the making of this blog post. The unlucky little plant was replanted into a different pot when the photo shoot was over.

In this photo you can see the adult leaves called the Epicotyl leaves growing in between the Cotyledons. This plant is considered a Eudicot because it has two Cotyledons instead of one. Plants with one Cotyledons are called Monocotyledons and the consist of things like grasses and palm trees. This plant will never grow cotyledons again for the rest of its life.

In a couple more years the seedling will resemble its parent the original Sporophyte that started this whole process. With full vibrant colors that change depending on the frequency of light they are receiving.

Once mature the sporophyte will flower and start the whole process over again. Hopefully this page made it a little less confusing for you instead of more confusing. In all honesty it took me a long time to even start understanding the alteration of generations in flowering plants. I think learning about Bryophytes helped with that… Maybe I’ll write about them in my next post?

With lots of practice though it becomes easier and easier to understand the processes. Specifically if you focus on the different flowering organs and how they interact with one another.

Finally, I’d like to say thanks for swinging by to read all this, if you’ve even made it this far, and to end it I’ll attach a few more photos of different angiosperms I captured this season at my Nursery. See if you can practice what you’ve learned here to identify the main different organs! Goodbye! Stay safe!

An unidentified wildflower growing out of a display at Truckee River Rock and Nursery Co.
Dianthus sp.

Author: garesgarden

ISA Certified Arborist, Amateur Botanist, and future Agricultural Engineer.

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