Added the fruit: now I think subsp cordata is a better choice
No interactions present.
I think the leaflets would be much broader in ssp sativa and the flowers 2-coloured. Con-coloured flower suggest ssp nigra.
V. nigra would have flowers 10-17mm and leaves 1-4mm wide. This one here has bigger flowers and leaves. Also teeths of calice are often smaller than corola's tube (here they are longer)
Could be V. cordata but need the fruit
Vicia cordata is apparently another name for ssp nigra.
Looks like subsp. nigra to me.
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