The warnings describe an invasive alien that will cause horrible burns to the skin of any human that comes in contact with it. We are told to observe but keep our distance, and report any sightings to the authorities – the invader is beautiful but vicious.
Another Russian spy plot? The story line for a new science fiction/horror flick? No, although the warnings read as if they could be about something from some other solar system. In this case, the subject is not a malevolent life form from a distant planet, but an attractive plant that might make an interesting addition to a flower garden.
In fact, that is probably how giant hogweed ended up in Canada. Decades ago, someone brought it here as a garden ornamental from Asia, where it originated, or Europe. Giant hogweed has been described as looking like wild carrot on steroids, with dinner-plate sized flower heads, glossy serrated leaves, and purplish stems. It can grow several metres in height.
The problem is that like a lot of alien species (for example, starlings in North America and rabbits in Australia) it did not have the decency to remain where it was wanted. Outside its natural environment and any natural controls, it spread quickly. One giant hogweed plant can produce tens of thousands of seeds in a season, and if they get into a waterway, the resulting infestation can take years and great effort to eradicate.
Then, of course, there is the problem of the plant being toxic. If the sap gets on the skin – or worse, in the eyes - exposure to sunlight causes horrible burns that can take months to heal and result in purplish or blackened scars. Children have been known to make pea shooters from the hollow plant stems, with deadly results.
The recent discovery of giant hogweed in Toronto triggered a rash of warnings about it. It seems “the world ends at the Toronto city limits” syndrome strikes again. One would think from the tone of the news stories that the plant had never been seen before in this country, but unfortunately it has become quite familiar to people around here over the past decade or more.
So have other alien species. The sea lamprey wreaked havoc on native fish species in the Great Lakes. The Asian swamp eel will likely show up in Canadian waters before long, if it is not already here, and promises to be worse than the lamprey. Plants including purple loosestrife and phragmites have been choking out native species along our waterways and in our marshes.
Then there is the zebra mussel. The small clam-like creature is back in the news because it appears to have triggered an algae problem in the Goderich area. The zebra mussel strains nutrient particles from the water and makes it clearer, allowing sunlight to penetrate to greater depths. This causes algae growth, and on occasion the stuff gets washed ashore, starts rotting and creates a smelly mess.
Asian carp, African bees, Himalayan balsam - the list of alien invaders is growing longer by the day, an indication of how small our planet has become. The great oceans are no longer a barrier to travel, be it a human in the first class section or a small hitchhiker in the form of a plant seed.
Summer is when a lot of people travel outside the country. Some of us might be tempted to sneak a few plant seeds, a root or even an animal product back into Canada from some exotic vacation spot. Bring back pleasant memories or even a picture or two, but give careful thought to giant hogweed before smuggling a few seeds for the flower garden.
The most opportunistic and dangerous alien invaders are probably viruses – the H1N1 virus made its way around the world in a very short few weeks. Before visiting a foreign country, do some research, update any recommended inoculations, and take sensible precautions against disease. The possibility of getting one’s wallet stolen by a street thug seems a minor danger compared to some of the more virulent diseases that could be lurking in the local water supply of your vacation paradise.