Yellow flowering plant, poisoness to horses.
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In my opinion, Ragwort can put on a fantastic display and is of great benefit to many insects including butterflies and moths. It is however, as you say very poisonous to horses and other livestock
Please see my Flickr photo's www.flickr.com/photos/129804972@N07/
A fantastic plant for insects and one which should be encouraged. As allrounder says, it looks really impressive at the moment and is a magnet for all sorts of flies, beetles and so on. Much hysterical nonsense is spoken about the threat to horses. It is worth looking at Buglife's site, where the issues are explained...
My Flickr photos...
Lat/Lng: 54.5, -5.6
OS grid ref: NW7120