Can someone name this plant seen on Guernsey near the coast in late June. Its 5 petals were probably separate and beneath it was a tangle of stems.? I did not take a specimen, thinking such a distinctive plant would be easy to identify. See attachment photo. From memory the flower diameter was around 2 cm.
Yes - you're right definitely Geranium maderense. There is often a lot of confusion over these big Macaronesian Geranium's and they are regularly mis-identified. Interestingly Stace mentions that Guernsey "maderense" plants are G. reuteri (G. canariense as was) - that plant is smaller, the central leaflet is sessile (which we can't see) usually less glandular -hairy and the throat of the flower is paler not darker than the petal-limb. The pinkish styles (not white) also confirm this. It would be useful to know exactly where on the coast it was?