I saw one of America's Most Wanted while driving to work today. It was unmistakable, though I had to stop the car to be sure. There by the roadside growing halfway down the embankment but still high above the guardrail, were the enormous stalk, leaves and flowers of Heracleum mantegazzianum: the notorious Giant hogweed.
I must have driven passed this plant all growing season without noticing it, which might seem remarkable for a species that can grow a dozen feet high or more. This one was about 5' above the roadgrade, and about the same amount of plant downslope in a tangle of poison ivy that discourgaed closer inspection. The thing that cause my eye were the massive inflorescences: huge platters of flowers that looked a bit like Queen Anne's Lace on steroids. If it had not been in bloom, it might have escaped detection.
That's the challenge with new incursions by invasive / exotic species. There is often a delay between the time when they take hold in a new place and when they are observed and recognized for what they are. The mantra of invasive species control is early detection and rapid respponse, because for many of these organisms it becomes exponentially more difficult to eradicate or contrain them with the passage of time.
Heracleum mantegazzianium has been around for a long time. It was introduced horticulturally, as so many of these species were before their invasive attributes were recognized, with the first record of its planting back in 1917. The shady, moist areas in which it particularly thrives have not been especially overrun with Hogweed run amok, at least in where it is just gaining a toehold, but the plant I observed clearly had escaped from cultivation. There is a known population of the plants in Cornwall Bridge, Connecticut, a mile or so from where this one was observed, and utility wires above probably provided the perch for the bird which was the vector for the spread of their seed.
Hogweed, however, has one additional attribute which has made it a top priority for State and Federal noxious weed eradication efforts. The plant contains the toxin furocoumarin, which can make skin highly photosensitive, causing weeping blisters and permanent scarring. Contact with the eyes can cause blindness. For these reasons, authorites consider a threat to public health.
The plant superficially resembles cow parsnip and Queen Anne's Lace, but its size at maturity is a dead giveaway, especially when in bloom. I did my part for early detection and reported this finding, along with photographs and detailed information about its location, to Donna Ellis of the Connectticut Invasive Plant Working Group; Elizabeth Corrigan, who is responsible for coordinating rapid response efforts for this plant in our region [email protected]; and Les Mehrhoff at the Invasive Plant Atlas of New England. It turns out that Corrigan drove by the same site on the same day and by her account "nearly drove off the road" when she saw the plant.
It is fortunate that I have lots of connections in the New England Invasive Species world, and that we have the chance to get this plant before all those seeds rain down. Who knows where else it may be lurking, unnoticed, out there in the wild?