Siskiyou aster

Symphyotrichum lanceolatum ssp. hesperium is a subspecies of the Symphyotrichum lanceolatum plant, commonly known as Siskiyou aster or western aster. This subspecies is native to western North America, particularly in California, Oregon, and Washington.

Symphyotrichum lanceolatum ssp. hesperium prefers full sun to partial shade and well-draining soil. It is often found in meadows, open woodlands, and along roadsides. In the mountain west it is also found in cordilleras.

This subspecies is differentiated from ssp. lanceolatum by characteristics of the inflorescence. The flower heads are usually subtended by larger, broader, leaf-like bracts. The outer bracts of the involucre (phyllaries) are longer, more than two-thirds the length of the inner ones.

Sources

3, 4, 28, 29, 30.

This and other asters were formerly place in the genus Aster. That genus was problematic, in that it did not include just one common ancestor with all of its lineal descendants and no others – it was not monophyletic. In 1994, the genus Symphyotrichum was resurrected to include most North American asters formerly in the genus Aster.