In the middle of the banks of yellow crucifer along the track back from Flamingo Pool, I suddenly spotted an Asteraceae with sagitate lobes surrounding the stem. It immediately shouted the sowthistle picture I'd been struggling with in County Down, and when I got it back home it looked very like one, with one of the leaves half way up the stem being superficially exactly like the picture in Francis Rose of the lower leaf of the Marsh Sowthistle.
However you cannot do Asteraceae like this, and the involucre should have been covered with blackish sticky hairs, which they were not. Saved by the hand-lens from making a horrible mistake! So starting again I looked at the other possibilities, and by elimination it started to look like a Hawksbeard, and a Smooth Hawksbeard, Crepis capillaris, at that. And that is was it turned out to be: The leaf I was looking at must have been an intermediate form as it was half way up the stem, and I should have been looking for the basal rosette leaves. As I wasn't, the pictures in Rose are almost entirely misleading, and I need to learn that lesson very carefully.
Here you can see the whitish outer surfaces on the outer ring of ray florets, which I cannot find mention of in the floras, but is in many of the images on the web. In this plant there is also a distinct and clear tiny orange tip to some of these florets. At the bottom of the picture above you can also see the developing inflorescences, which are held vertically in life (thank goodness for turgor pressure I say!) and also shows the adpressed lower ring of phyllaries. I would have said the stems were ridged and hollow (one of the characteristics that helped me towards my initial and misleading id of Marsh Sowthistle!).
You start off by identifying that all the florets are ray-florets, with no disc florets to be seen. This takes you into Group A, the quite large and diverse group of Dandelion-like Asteraceae. Then you look at them as yellow florets, with at least some stem leaves, so eliminating Dandelion itself, but then you can't get much further if it is without fruit (achenes), so it's back to eliminating the unlikely and impossible, such as the Lettuces (characteristic branching or spike like inflorescense with smaller narrow involucres), Cats-Ear and the other hawkbits (upper stem not leafy), Mouse Ear Hawkweeds (furry leaves) and Nipplewort . Then Crepis, the Hawksbeards starts to be a possibility in amongst all these others. I didn't think it was a Hawkweed as I don't know any Hawkweeds with these backward lobes, all the leaves seem to be fairly simple entire ovate shapes.