Publication: Phytologia. 77: 283. 1995.
selected vouchers: WTU
Notes: FNA20: "Symphyotrichum hallii is restricted to open habitats of the Puget Trough of western Washington and the Willamette Valley of western Oregon, with outlying stations in the Columbia Gorge and central Washington. Some of the polyploid races appear to be alloploids involving the sympatric S. subspicatum, with larger leaves and fewer, larger heads with violet rays."