Marigolds and Life

This is a story about marigolds - ostensibly about marigolds. It could be about some other plant, but it isn't.

I like to grow marigolds, almost to the extent it's a mania, but not because I think they are pretty or because I want the yard to look nice. I grow them because I like to see the variety of life. I like to see the process, of taking a seed and making a plant. I like to see how how seeds from a plant can come out the same as their parent plant, or very very different. I like to see how some plants do great, and some plant do poorly. I like to see the ones that struggle, and what makes them different.

Let me show you some pictures.

Here is a photo of some marigolds that I have grown from seeds in my front yard. All these came from the same seed packet, yet you can see one is very different! It is giant!

Now this may or may not be amazing to you, there are a couple of explanations, and it would help if I told you more about marigolds in general.

Marigolds, or what are commonly called marigolds, fall in two types. "French Marigolds" (which are also known by their scientific name, Tagetes patula, or abbreviated T. patula) are small growing and have flowers that can come in a wide range of colors and forms. "African Marigolds" (or Tagetes erecta) are much taller growing, and tend to all be more standard looking, either orange or yellow or white.

Despite their names, both types of marigolds originated in Mexico and Guatemala, and have long been grown by humans, even as far back as the Aztecs. In 1961, so and so did a careful series of experiments which showed that the smaller T. patula probably arose from a cross between the larger T. erecta and a closely related species. Not only that, T. patula are probably allotetraploids, meaning simply they have four sets of chromosomes whereas most plants are diploids, or have two sets, and that they have two sets from each hybrid parent.

Normally organisms, like you and me, get one set of chromosomes from one parent, and one set from the other. This is the same for just about everything. Well, at some stage it seems things went a little weird, and for some tetraploid marigold, it got two sets from each.

Typically, when two related species make a hybrid, their chromosomes being a little different, they don't match up right during the plants growth, and the plant is weak or doesn't life at all. With a allotetraploid, the chromosomes do match up since it has two from each parent and the plant survives, and may even do better. If it does, it becomes a species on it's own, as seems to be the case with T. patula.

Tetraploids often look very different from their diploid parent. Their growths tend to be stockier or flowers larger. In the case of Tagetes patula, the plants are more compact. In the above mentioned paper, the authors produced allotetraploid hybrids using T erecta that very much resembled T patula. So it seems T. patula is an allotetraploid that originated from T. erecta.

So what does this have to do with the picture? It appears one marigold that is supposed to be T patula is growing more like T erecta. Perhaps it is a diploid "throwback". Sometimes mistakes happen in the formation of a seed and the embryo only has half the chromosomes it's supposed to. Usually this is fatal, but maybe the tetraploid parents gave rise to this diploid plant. Maybe this is an offspring of T patula that will look more like T erecta.

Maybe, however, this is just a T erecta seedling that got in a packet of T patula. This is why I want to raise my own seed, to be sure this didn't happen.

Here is another picture.

Look at these two plants from the same seed packet as their neighbors, and the giant one I showed previously. They are much smaller and weaker than their neighbors, like the one circled in orange. Why? Maybe they have some genetic novelty. Maybe they are being beset by some pest or suffering some unknown growing condition. (The fact that they are growing next to each other seems to suggest this - the odds that two similar genetic difformities are growng next to each other is much less probable than one alone.)

How often do these things happen? When you see marigolds in someone's garden, they do tend to look the same. Maybe these weak ones or freakish ones are pulled out. Maybe this is standard practice in seed production, uniformity is what most people want for their garden borders.

Well not me. I like weirdness. I want to see how weird a marigold I can find. How big, how small, how twisted can they get. Most marigolds have pinnate or fern-like leaves. Maybe some don't. Maybe there are some smaller un-marigold looking flowers that occur and could be bread. I want to cultivate unusual marigolds, raise my own weird strains and explore the genetic diversity of this group of plants.

Part of my motivation here is work done by Blakeslee years ago, and summarized quite nicely in the book "The Genus Datura" Blakeslee worked with Datura stramonium, or Jimsonweed, and it's relatives. He raised and crossed many Datura and found and explored many unusual genetic varieties. Can the similar thing be done with marigolds. I shall see.

I am fortunate that much breeding has already been done with marigolds. There already is a wide range of varieties. Marigolds themselves have interesting histories - they are regarded as the flowers of the dead by some native American peoples and are used to welcome the dead back home in the mexican dia de los muertos celebration.

Aside from that, and more fundamentally, there is the wonder of a plant growing from a mere seed. It is an amazing process that we often overlook. Because we understand some parts of the process, or we have seen it happen over and over, we have disregarded the wonder of this process. Watching a small plant push it's way out of the soil and develop into a large flowering plant is an amazing thing.

It is with this sense of wonder I present to you the marigold. I hope you will find some interest in this wonderful, ever unfolding story.