Eucephalus glabratus (Greene) Greene is native to dry open oak or coniferous forest or chaparral in the Klamath Mts. of northern California and southwestern Oregon (Allen 2006 FNA).
The images posted are from a populations further south in the Coastal Ranges than the Klamath Mts. The images are posted as E. "aff." glabratus and may represent marginal population variant. The 0-4 rayed taxa in the genus are difficult to distinguish in northern California and may intergrade (Allen 2006 FNA).
The following names are synonyms: Aster brickellioides Greene var. glabratus Greene, A. siskiyouensis A. Nelson & J. F. Macbride, Eucephalus glandulosus Eastwood.