Tuesday, September 25, 2012

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!

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