Is this Robinia? I saw this plant in bloom when there were right time for Robinia. But it is still in bloom and last summer I remember flowers were very late. 19-21 leaflets with so strange apex at each.
What is this strange thing at the end of leaflets? Is this a feature of this particular Robinia or it is common?
A bristle, from the leaflet midrib extending beyond the normal leaflet apex. It's not standard on Robinia, but might be a feature of that particular individual cultivar.