Last summer we were intrigued by the flowering shrubbery, or annoyed by the messiness of some of the residents. One blob of greenery did nothing much the whole year. This year it unexpectedly threw out dozens of loose panicles which opened into tiny four-petaled flowers. It is clearly related to the lilacs, but with more honeyed yet somehow sharper scent to me. It is probably Syringa x persica, a natural hybrid called Persian Lilac, but obviously this is a guess rather than a decisive identification.