The most hated plant in North America

Today is a very special blog post, brought to you by one of my very best(est) friends, Tanya! Everyone say Hi to Tanya! (Hi Tanya!) Tanya gets to work outside all day every day (OK, not all day every day, but she gets to be outside A LOT with her job), and has some really awesome pictures of really unusual plants in North America. This one certainly isn't uncommon, but that doesn't make it any less special! This blog is her first (of hopefully many!) guest post for my blog, and she's writing about a plant most of us absolutely hate. And if you don't know if you hate it...do you get a runny nose and red, itchy eyes in the fall? Yes? Then you hate this plant. Trust me :)

Without further ramblings by yours truly, take it away Tanya!

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Species name: Ambrosia artemisiifolia

Common name: common ragweed, annual ragweed

Location: top image from our guest contributor; images 2, 3, and 5 from melody at Dave's Garden (available HERE); image 4 from htop at Dave's Garden (available HERE)

There may be another plant that a greater number of people despise (dandelions, maybe?), but for sheer intensity of feeling, I would argue that the most hated plant around must be Common Ragweed (Ambrosia artemisiifolia).  Every year in mid-August, many of us get that old, familiar itchy-eyes and runny-nose feeling that sends us running for filtered, air-conditioned air and antihistamines, and Common Ragweed is most likely the culprit.   

As Jen mentions in THIS POST, many people blame their fall allergies on showy flowering plants like the innocent goldenrods.  But, in order to cause your allergic reaction, you must breathe in the pollen grains, which means that the plant you’re allergic to is wind-pollinated: the plant produces lots and lots of pollen light enough to be blown around in the wind, and it’s betting that some of it will land on the female parts of another plant of the same species.  Plants that use this strategy have small, inconspicuous flowers because they don’t need to expend energy to attract pollinators like bees and butterflies to carry the pollen around for them.  Common Ragweed falls into this category: its pollen can be carried by the wind for hundreds of kilometers.  It’s hard to get away from this stuff.

Common Ragweed is native to North America (Jen says: I put "non-native" for the species status so that I could have a diagram with the "Invasive" box highlighted!) but has become an invasive species in Europe and Japan.  It is a “supertramp” species (yes, that’s a legitimate ecological term), which means that it produces lots of seed, disperses widely, and does really well in disturbed habitats. When you start looking for Common Ragweed, you’ll most likely find it in highly disturbed areas, like beside roads and in agricultural fields rather than stable forested areas, so really, it’s all our fault there’s so much of this stuff around: we’ve created lots of habitat for it!  There’s probably much more Common Ragweed around now than there was when Europeans arrived in North America.  You can burn it, pull it, mow it, or kill it with chemicals, but it will most likely come back in full force the very next year.  A good argument for increasing the amount of healthy forest and grassland habitats where Common Ragweed can’t compete, I say.

Ragweed leaves are compound and finely divided, and look a little like Wild Carrot (Daucus carota, which you can read all about in THIS POST) or Yarrow (Achillea millefolium, which you can read all about in THIS POST).  The flowers and seeds are produced in a tall spike called a raceme, and the plant grows to be about one meter in height.  This means that, in many areas, it isn’t completely covered by snow throughout the winter, and any of the seeds remaining on the plant remain accessible to animals like birds and small mammals.  The seeds have a very high oil content too, which makes them even more valuable to wildlife.  When Common Ragweed is causing you or your loved ones autumn misery, think about the mice and voles that will be depending on their stored ragweed seeds to survive until spring... and in the process, spreading them all over the place so there will be lots more for next year!

Painting the fields gold: goldenrods

Species name: Solidago canadensis

Common name: Canada goldenrod

Location: Ontario

Canada goldenrod is one of the few plants to be accidentally exported to other countries around the world that has since caused enormous economical and ecological damage. Most of our native species, it turns out, are little more than "mildly" invasive once they reach foreign habitats. This plant, however, is one of the few, shameful, exceptions. Goldenrods in general get a lot of bad press in the fall. A lot of people seem to think that goldenrods are the source of their seasonal allergies, but this is far from the case. Goldenrod pollen is ENORMOUS as far as pollen is concerned, and based on the number of bees swarming around goldenrods in September it should lead you to believe they are insect-pollinated (which they are). Goldenrod pollen is also sticky and has large spikes to stick onto the tiny hairs of the legs of bees to be carried to the next flower. Ambrosia, or ragweed, is flowering at much the same time as most goldenrods and is the source of hayfever. Its pollen is much smaller (about half the size of a goldenrod's pollen), and the flowers are wind-pollinated. The pollen swirls around in the air currents, often being inhaled by various vertebrates. Because the pollen is so small, it causes irritation in the nasal and respiratory passages and causes sneezing and congestion in those that are sensitive. So if you're miserable with a runny nose in the fall, make sure you're blaming the right plant for your pain and suffering!

Goldenrods were accidentally introduced to many countries in Europe and Asia, and purposely introduced to Britain where it has taken off as an ornamental garden plant. In fact, there are some areas of Britain that have "goldenrod collections" and actively breed new species. Us Canadians find that hard to believe since it's a common weed here, but I guess to each their own. In fact, it has been gaining slight popularity in North America as an ornamental species where the planting of native species is promoted. Unfortunately, it's also a wonderful example of exactly how invasive species work. Since its accidental introduction to China, especially the province of Shanghai, the plant has reached epidemic levels. It is estimated that it has directly caused the extinction of at least 30 different native species due to its strangling effects. It has also reduced orange yields due to its ability to compete for resources. The sightings of various species of goldenrods is even taken as seriously as terrorism threats in some highly sensitive areas of China! It has also caused widespread concern in Germany, where it has started displacing some native species in sensitive areas.

Believe it or not, most parts of the goldenrod plant are edible. The flowers, while not overly appetizing, are considered edible, as are the leaves and young shoots. I've never tried eating them (OK, I've tried the flowers...I don't recommend them!), but they were once heavily relied on by native North American people during years of low yield of agricultural species. This year would be a prime example of a goldenrod eating year: corn fields are rather sad looking, yet roadside ditches are absolutely full of goldenrods! Some species have also been used medicinally as a treatment for pain and infection associated with kidney stones. As far as I know, no scientific studies have ever been conducted to determine if this effect is real, or if the warm tea acts as a placebo effect (as most warm tea does!).

I learned recently from a friend who owns two beehives that goldenrods are sometimes planted on purpose near apiaries to make "goldenrod honey". I didn't realize this would be any different than any other kind of honey made in the fall, but perhaps that's because I wasn't thinking about why I didn't like goldenrod flowers. The honey made from goldenrod flowers actually tastes like it has had black pepper infused in it, and has a very spicy aftertaste! It's amazing how bees can use different species of pollen and nectar in the same way and end up with entirely different products. Nature is a fascinating thing!