Flower power is an old-fashioned way of referring to hippies and the culture associated with hippies in the late 1960s and early 1970s.
...the era of ~.
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FLOWER POWER
Meaning of FLOWER POWER in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012