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blowin · Posted: Fri May 25, 2007 2:09 am Post subject: photoallergenic plants

The type of plant which can cause very severe blisters and scarring if its sap gets onto your skin in sunlight ( but normally doesn't if it is overcast ) .
The Giant Hogweed is widely publicised and is quite distinctive but does anyone know what the others are ? I know that ivy can have this effect on some people but that is not a common reaction . I am trying to identify something which has very recently caused unpleasant and quite extensive blistering on a friend's arm . This while strimming an area which was somewhere between a lawn and a hayfield ( seriously -- I mean there was nothing particularly unusual about the vegetation , no obviously large umbellifers but there was a broad-leafed sappy plant ) . A similar thing happened to another friend working in an overgrown garden last year so it can't be that rare .
Any thoughts about treatment ?
I haven't had much luck on google so far but will post links if I can find anything useful .

chook · Joined: 14 Mar 2007 Posts: 305 Location: North Clare

I got a nasty dose of that many years ago on a cycle trip in the Pyrenees. Sat on a hay bale in a shed wearing short trousers. The next day, once the sun hit the legs, I got nasty blisters which took weeks to heal and were still visible as scars a year on. Talked to a doctor friend and we went through some books together back home and came to the conclusion that it was probably Burning Bush (Dictamnus albus).

St. John's Wort (Hypericum perforatum), if taken internally, e.g. as oil, can induce photosensitity.

Buckwheat (greens/seeds) is also known to induce photosensitivity in livestock if consumed in quantity.

chook

blowin · Posted: Wed May 28, 2008 12:45 am Post subject:

This is only an educated guess but I think the offending plant is a low-growing member of the spurge family . The one with small yellow flowers ( brachs ) . Several are illustrated here http://www.irishwildflowers.ie/s.html .
I understand that all members of this family can cause a reaction in strong sunlight . They have a thick , white sap .