Thursday 16 July 2015

Giant Hogweed in the news

Giant Hogweed in flower
Image courtesy of J. Crellin
Barely a day seems to go by without another media report about another incident of somebody having a close (and often painful) encounter with a Giant Hogweed Heracleum mantegazzianum. 

Some of the reports are quite alarming but where has this plant come from, is it on the increase and how dangerous is it?

Ian Denholm, BSBI President, and Kevin Walker, BSBI Head of Science, have been in great demand from journalists asking where Giant Hogweed comes from originally (the Caucasus Mountains), when it was first introduced into Britain & Ireland (first record is from 1817), where and when it was first recorded in the wild (Cambridgeshire, 1828) and whether or not it is increasing.

Fortunately these answers were all at our fingertips, thanks to both the BSBI Distribution Database and New Journal of Botany (NJB), our science journal. 

Giant Hogweed records.
Downloaded 15/7/2015
Courtesy of I. Denholm
Although NJB is only available to BSBI members and subscribers, one of our current 'Editor's Choice' papers is this one about Giant Hogweed, published in 2013 and now available free to view and/or download. 

The paper has lots of info about the plant's history in Britain and about the furanocoumarins (the chemicals responsible for Giant Hogweed's fearsome reputation), which were present in every sample the authors looked at. 

They concluded that the plants "pose a potential threat to the general public and the priority given to their eradication, particularly in amenity areas, should be rated accordingly".

And the BSBI Distribution Database? Click here to see our interactive map for Giant Hogweed: you can zoom in to any 10 x 10km square across Britain and Ireland and see whether the plant has been recorded there in six different date-classes, starting with pre-1930 records and ending with the current date-class, which started in 2010 and closes with Atlas 2020

So, is Giant Hogweed increasing? In the map (above left) - the result of Ian interrogating the database earlier today -  each shaded square indicates where the plant is recorded right now. See also this article in The Express which uses a rather snazzy version of our distribution map for Giant Hogweed, giving totals across the decades. 

Giant Hogweed in leaf
Image courtesy of J. Crellin
Anyone can zoom in to our distribution maps to a certain extent (and are encouraged to do so!) but if you would like greater access to the latest data, showing which wild plants are growing where and how this is changing, then you will need to join BSBI and get involved in our botanical recording community. 

If you are already a BSBI member, please email Kevin or Alex if you would like to request greater access to the database. 

If you are unsure how to identify Giant Hogweed, there are some helpful pointers on this factsheet by Irish botanist Oisin Duffy or try the Environment Agency's factsheet here. While out botanising, if you encounter a Giant Hogweed, handle with care, don't get burnt and don't forget to check the BSBI database - is the plant recorded in your locality?

If not, please send your record of it to your County Recorder, so we can build up a clearer picture of where Giant Hogweed is growing across Britain and Ireland.

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