The name Zeltnera muhlenbergii (Griseb.) G. Mansion is here applied to a species native from Monterey County, California, to southwestern British Columbia. From Z. davyi (Jeps.) G. Mansion, a California endemic to which the name Z. muhlenbergii has sometimes been misapplied, Z. muhlenbergii differs in that its calyx lobes are not keeled or have keels proximally only, to 0.25 mm wide, and its corolla lobes are 1–2 mm wide; in Z. davyi the keels of the calyx lobes are 0.3–0.6 mm wide and the corolla lobes are 2–3 mm wide. Zeltnera muhlenbergii has often been confused with Centaurium tenuiflorum (Hoffmanns. & Link) Fritsch ex Janch. s.l., a species naturalized from Eurasia, now established in Pacific and Gulf coastal North America. From C. tenuiflorum, Z. muhlenbergii differs most notably in its flabelliform rather than ovate stigmatic lobes and in its more open, non-corymboid cymes.