Sandra's Garden: proof not all Phlox are created equal

Species name: Phlox subulata

Common name: moss pink, moss phlox

Location: Sandra's garden

Last year I posted a blog about moss phlox, a native species we have in our garden that gets a little out of control in really sunny areas. It's a species native to North America, and one that occurs relatively commonly throughout its native range in bright and sunny, damp areas (despite also being drought-tolerant). It is much more common in the United States than in Canada. I knew this species was a popular garden plant based on what I've read about it, but I had never seen any of the cultivars created in greenhouses aside from the "normal" light purple type. Well, here's a spectacular demonstration of the "hidden" morphological variation that some plants contain. This variety of moss phlox was not created in the lab, but is a product of controlled breeding. Despite this, you would never find this variety of phlox in the wild unless it escaped from someone's garden.

So how do we "create" morphological variation in plants that is not typically seen in the wild? The secret is some patience, and a lot of time on your hands (it helps to have a greenhouse because it speeds things up a bit). Natural mutations in the wild create different alleles, or copies of a gene, that can show different morphologies if they have a chance to be expressed. Most of these mutations are what we call "recessive", which means you have to have two copies of the gene in order to be able to see the effect. This is good for the plant if the mutation is detrimental, but bad for gardeners if the mutation is something we want to see. In order to increase the number of recessive mutations in a population you back-cross the plants (breeding a daughter plant with a parent plant), or force inbreeding (forcing a plant with the gene to pollinate itself; sometimes this isn't possible in plants). After enough generations, which can be anywhere from 10 to over 1000 generations to get a pure line, you have a plant that shows only the allele you want expressed. Most garden plants are created this way; you back-cross over a certain number of generations until you get the desired effect in nearly all seeds grown. A huge downside of this type of selective breeding and back-crossing is that you're decreasing the genetic diversity in a population by selecting the alleles you want expressed and eliminating all others. For most plants this isn't a big deal; the ones grown in gardens are hardly reflective of the population as a whole in most cases, and if a virus or fungus or bacterium evolved that could eliminate an entire population of ornamental plant because of the inbreeding and a lack of resistance it wouldn't matter much. You would replant the next year with a different variety and hopefully the problem is solved. The big problem occurs when we start doing this with crop species, as we have been doing for over 12,000 years. Corn, for example, is so susceptible to disease that it is completely unable to survive without human intervention (not to mention we have eliminated the corn plant's ability to disperse its seeds; this is a slight problem if you're a corn plant but a major benefit if you're a human wanting to eat corn seeds). Soybeans in North America right now are on the verge of a massive population collapse due to the fungal disease called the soybean rust. It has recently shown up in the southern United States and is attacking soybean crops that have all shown to be susceptible to the disease. We grow the same variety in Canada (bred to have an increased seed size with an increased oil store in the seed), but are only saved from the attack of the pathogen due to our much colder winters that the fungus can't survive. It's only a matter of time before an entire year's crop is wiped out which could be absolutely devastating to the North American economy.

The previous blog post I did about this plant (which you can read about HERE) mentioned the smell of marijuana that this plant supposedly has, and the drug busts that have occurred as a result of people innocently growing moss phlox and having the smell waft in the wind. I did pick some leaves and crush them up; if you use your imagination I guess it smells like marijuana. I have a hard time believing that it would produce enough of a scent to convince someone there's a drug op in their neighbour's back yard, and I also have a hard time believing that someone would mistake the smell of phlox for the smell of marijuana!

A monster looms in the bluebells...

Species name: Taraxacum officinale

Common name: dandelion

Location: Ontario

Feeling like you have deja vu? That might be because I've already blogged about dandelions before, but they were regular ordinary dandelions. This one is special! If you'd like to read my last blog about dandelions and learn a whole bunch of cool stuff about dandelions in general, you can do so HERE.

Dandelions are most likely native to Eurasia, but there's a significant debate about their origins. There have even been a few people to suggest that the true dandelion that carries this species name is only found in North America, and that there's a separate species in Europe. The Europeans always feel they have to be special... :) Regardless of the true species name, almost all dandelions are created equal: they flower in the spring when you're just trying to get your grass looking good again, most people hate them, they have taproots that are nearly impossible to get out of the ground unless you're weeding after a heavy downpour and the ground is wet (if you've never weeded after it has rained, give it a try. You'll thank me later. You're welcome), they have bright yellow flowers that turn into fluffy seed heads, and no matter what kind of biological warfare you use on them the always come back. You know, typical boring (some might say ugly, but I rather like them) dandelions.

Except this one!

Instead of just talking about why dandelions are cool, I wanted to talk about why THIS dandelion is cool. You can see right away from the top image, highlighted in the bottom two images, that the flower head of this particular plant doesn't look like a typical dandelion plant. This phenomenon is called "fasciation", and so this dandelion plant is fasciated. This means that all of the flower heads that would have developed into their own flower under normal conditions have, for some reason, fused together and created a mutant giant flower head (caused by the fusion of many separate meristems at the end of the inflorescence stalks). This, to me, is one of the most fascinating phenomena of the plant world, and has been documented in over 100 species of plants. The best part? No one has any idea why this happens in any given plant. There are lots of ideas of why this might happen in general: exposure to radiation, attack of a virus, exposure to low doses of specific chemicals (like 2,4-D, or Roundup, for example), mechanical disturbance, insect damage, or genetic mutations. But could anyone tell you why THIS PLANT became fasciated? As of our current knowledge, no. You could definitely speculate and come up with the most likely scenario but you would never be 100% sure (and there are likely other reasons why this happens that are currently undocumented). Normally this phenomenon is incredibly rare in the plant world, and to see it would be a real treat...except dandelions. Apparently dandelions do this all the time! Silly plants. The speculation here is that in this plant species it is more than likely pre-determined by genetic mutations that can be passed on through the seeds, but also exposure to common pesticides like 2,4-D also play a role (and dandelions are always on the end of chemical attacks, it seems!). Unfortunately, someone ripped this plant out of the ground (and by someone, I mean the people that do grounds maintenance on campus) before it had a chance to finish flowering and turn to seed. I would have loved to continue taking pictures of the flower development and collect some seeds to see if I could grow a new fasciated dandelion! Yes, I know what's coming. "You know you're a nerd when..." :) Don't worry, Mom and Dad. I would have done it in the greenhouses at school!

Have you ever seen a fasciated plant? Now that I know it exists, I saw the remains of a fasciated tulip growing in a bed on campus. Fascinating fasciation!

EDIT: I guess I should mention that this phenomenon isn't just restricted to the plant world; it also happens in fungi. Next time you're in the grocery store and have some time to kill, go pick through the bin of shiitake mushrooms. I bet you'll find a mushroom with a single squashed-looking stalk with two caps on the top. Fasciated shiitakes are quite common; I guess that makes the shiitake the dandelion of the fungus world!