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The plant in the picture is Gaura lindheimeri, whirling butterflies. Also known as Indian feather. It has recently been reclassified as Oenothera lindheimeri so you may find it under two different names.
It is an almost shrubby perennial originally from Texas. We are at the top of it’s growing range here in Toronto. In the south they can be evergreen, not losing their leaves in the winter. In Toronto it will die back to the ground each year. They start blooming in the summer and continue right up the frost. I am including a link below if you would like to read further on this pretty flower.