Giant Hogweed (Heracleum mantegazzianum)
Common Names: Giant Hogweed, Cartwheel-Flower, Giant Cow Parsley, Giant Cow Parsnip, Wild Parsnip, Wild Rhubarb
Scientifc: Heracleum mantegazzianum
There are very few plants I'm genuinely frightened of, but the Giant Hogweed is one that I'm glad I've never encountered.
It's native to the Caucasus region of West Asia but it has been introduced as a garden plant and has successful spread itself along waterways as a weed throughout much of Europe and North America.
It's similar in appearance to many other members of the Apiaceae family such as common hogweed (Heracleum sphondylium) and Garden Angelica (Angelica archangelica) bar one distinguishing feature, it's truly a giant. Giant Hogweed has been known to grow up to a staggering 7 meters (23 feet) tall, although it's rare for them to get much larger than 5 meters (16 feet) tall.
Giant Hogweed gains its notoriety from its phototoxic sap. When the sap comes in contact with human skin it causes no harm in itself. However once the sap has been absorbed by the skin and the skin is then subsequently exposed to sunlight it triggers a reaction that leads to severe blistering. These blisters cause large, black or purple scars that can take several years to fully heal. If any of the sap gets into the eyes it can result in blindness which may even be permanent. If you are interested in viewing some gory pictures type "Giant Hogweed burn" into Google image search.
People clearing Giant Hogweed have to wear protective clothing including eye protection to avoid getting any of the sap on them. If some unfortunate person happens to get the sap on them it is advisable for them to wash the area immediately with soapy water, then cover the area and avoid any sun exposure on it for several days while the potential for blistering is at its worse.
Due to it's size, invasiveness and potential to cause harm horticulturalists at Maine State Univesity have nicknamed the Giant Hogweed "Queen Anne's Lace on steroids" after the weedy wild carrot which is also a member of the Apiaceae family. This is a fitting nickname for this terrifying, but at the same time rather fascinating, triffid of a plant.
The one saving grace in humanities fight against the Giant Hogweed is that it is short lived, rarely lasting more than 7 years. Nether-the-less the Giant Hogweed still manages to claim around 15,000 victims in Germany alone every year where it has become a serious pest.
Apparently pigs and cows are unaffected by Giant Hogweed and will happily munch away on it, perhaps we need to create a bovine and swine task-force to combat it. Bees also enjoy Giant Hogweed for the profuse quantities of flowers they produce, which unfortunately results in large numbers of seed also being produced.