No interactions present.
According to the BSBI maps this has never been recorded anywhere near Plymouth, so it is necessary to inform the county recorder.
The fruits do look to be drooping to one side as you say. I see the Plant Crib gives this information. On the other hand the Crucifer Handbook says that the fruits should be 2-3 times as long as pedicels for islandica. They seemed to me more like 1-2 times as long (palustris) but I may be wrong.
I think the best thing for me to do is collect some ripe fruits and send them to the BSBI referee for Rorippa.
Islandica is listed in Len Margett's 'Checklist of the Devon Vascular Flora', 2007, but not for VC3 (South Devon).
Thanks for your help.
The BSBI referee for Rorippa has looked at the photo and he is quite sure that it is indeed Rorippa islandica sens.str. so thanks for correcting my id. I have contacted the Recorder for S. Devon and given him the record.
It seems the BSBI maps are somewhat out of date. The South Devon Recorder has told me of two nearby records from Plymouth.
Why repeat the ID with exactly the same comment as I gave? Incidentally, the BSBI referee for Crucifers has told me he is not the expert mentioned who remains a mystery, but he does agree with the ID anyway.
The BSBI referee for Rorippa is Prof. B. E. Jonsell. He was kind enough to look at the photo and agreed with you that the plant is Rorippa islandica.
Apologies to him.
Lat/Lng: 50.3943, -4.0898
OS grid ref: SX515570
One plant growing on steps. West bank of River Plym just north of Marsh Mills, Plymouth