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!

When a flower isn't a flower: part 1

Species name: Bougainvillea spectabilis

Common name: bougainvillea, Napoleon, veranera, trinitaria (amongst others)

Location: Dominican Republic

Bougainvilleas are some of the most well known and well recognized tropical plants in the world. They originated from a relatively small band of South America, extending from Brazil west to Peru and south to Chile and Argentina. Depending on who you ask, there are between 4 and 18 species in the group (18 species is probably an over-estimation due to morphological variation displayed even in a single group of individuals, but I doubt there are only four species since diversity of plants in the tropics is so high). DNA sequence analysis definitely needs to be performed on this group to help not only with defining diversity, but also establishing if any of these populations (however isolated) are their own species and hence are in dire need of protection and conservation. One of the reasons why this is such a popular "resort plant" in tropical countries is because of its extreme ability to tolerate salt (it can tolerate being watered with seawater! That's salty!) it makes for an ideal ornamental species where salt spray (and periodic flooding due to storm surges) is common.

The "flowers" of the bougainvillea plant are great examples of how plants can entice animals into believing that they produce these large, showy flowers, but in reality produce small, barely noticeable flowers and fruit. The pink "petals" that many people believe to be the flowers aren't at all; they're just modified leaves containing pink pigments instead of green ones that act to attract pollinators (we call these bracts). The flowers themselves are the small white bits on the inside; there are usually three white flowers surrounded by three to six bracts. The bracts can be white, yellow, orange, red, pink, purple, green, or any colour inbetween. The only colour of bougainvillea bract that I don't think exists is blue; feel free to correct me if you've ever seen a blue one! There are over 300 different varieties of bougainvillea sold as ornamental plants, so it wouldn't surprise me if it had been "invented". Not only have there been hundreds of cultivars and varieties created through selective breeding, but bougainvilleas also naturally hybridize in the wild. There is even a population of plants in Peru, once thought to be a distinct species, that is a hybrid of two commonly found species. What's unusual about this hybrid population isn't the fact that it's a population of hybrid plants, it's where the parental plants are located. And that's nowhere near this hybrid population. There's no documented evidence, either, that either of the parent plants of this hybrid ever existed in this area of Peru. So how did they get there? Is this evidence of "early gardening" by native Peruvians? Is this evidence for population reduction in both parental species of bougainvillea? Can the seeds really be carried that far? Is there an animal vector (or was there an animal vector) that eats the fruit to disperse the seeds that we don't know about? Some fascinating questions with (so far) no conclusive answers.

Other than the ornamental value, this plant has no other uses to humans. The sap of the plant to some people is highly irritating to the skin; in people who are highly sensitive to the sap the reaction can be as extreme as it is to poison ivy. Other people either don't react at all or react with a slight rash and a mild itching. Luckily, unlike with poison ivy, a cut portion of the stem must come in prolonged contact with the skin in order to cause a reaction. This means that you should only be worried if you have been given the task of pruning a patch of bougainvilleas; if you have, make sure you wear a long-sleeved shirt and gloves and you'll be fine. This is also a very popular plant to turn into a bonsai (although, a different species is often used; B. glabra). The bougainvillea is the national plant of Guam, as well as the regional flowers of regions in China, Japan, Taiwan, Malaysia, Philippines, and the United States.

Stay tuned for part 2 of "When a flower isn't a flower" tomorrow, featuring one of the most commonly purchased plants for ornamental, indoor use.

One of the Austrian pines

Species name: Pinus nigra

Common name: Austrian pine, European black pine

Location: Ontario

The Austrian pine is native to Europe, in countries surrounding the Mediterranean and Baltic Seas. There are actually two subspecies of the Austrian pine which rarely interbreed (but are still capable of forming hybrids in a very small overlapping zone as well as when they are brought together under artificial conditions like a greenhouse): the western subspecies existing in southern Italy, southern Spain, southern France and North Africa and the eastern subspecies in Austria, central Italy and Turkey. The needles of the two subspecies are quite different and you can easily tell them apart when side-by-side; the needles of the eastern subspecies are much fatter and much more rigid than the western subspecies. They both have different liveable temperature ranges, too, with the eastern subspecies being able to tolerate much colder minimum temperatures (down to -40 degrees Celsius with no adverse effects) compared to the western subspecies (only about -25 degrees Celsius or so). I believe the subspecies on campus would be the eastern subspecies, P. nigra subsp. nigra.

One major attractive feature that probably led to its widespread planting across Europe and North America is that it is a very fast growing tree, relative to other needle-bearing trees. It was originally thought to be an excellent lumber tree, so it was planted in large numbers in North America. Unfortunately, the grain of the wood is very rough and quite variable across the height of the tree, so making long boards suitable for building is not feasible. It was turned to as a major source of pulp and fibres for making paper, as a fuel source, and is still used as a low-grade wood for some construction purposes.

Unfortunately, as with most plant species that have been transported out of their native range, the Austrian pine has a dirty secret. That secret is a fungus. The "red band needle blight disease", caused by the fungus Dothistroma septosporum, is especially toxic to North American Austrian pine trees because of their inability to breed properly here. Austrian pines have a hard time cross-breeding outside of their native ranges, and the seeds that are self-fertilized are much less likely to germinate. This causes something called "inbreeding depression," which can lead to a buildup of genes that make a tree (this happens in animals, too) more susceptible to a pathogen. The North American trees are very susceptible to this pathogen, and it is an almost certainty that every single Austrian pine tree in North America will succumb to this disease. There is no known treatment once a tree is infected other than cutting it down and burning the residues (especially the needles, where the pathogen is housed in the living tree). Planting this tree, even as an ornamental, is strongly discouraged and planting this tree in continuous stands is not only strongly discouraged, but carries quite a hefty fine if you're caught doing it in many states in the United States (but no provinces in Canada yet). You can see that the tree in the top picture is looking very unhealthy; it is likely showing the first signs of infection from the disease.