Heart Leaved Aster
Symphyotrichum cordifolium
Notes:

From what I've read, Asters are one of the best caterpillar host plants. The adult pollinators also like them.

Two - four foot flower with clusters of lavender blossoms. Very pretty in fall after summer flowers are done. Excellent for bees.

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Photos:
Don't blow it - good planets are hard to find.
Quoted in Time