Publication: Mém. Mus. Hist. Nat. 5: 50. 1819.
selected vouchers: WTU
Notes: Oregon Flora Project: "Although G. squarrosa is similar to G. nana in the form of its inflorescence and can sometimes be difficult to distinguish, the two species are rather distantly related and are unlikely to hybridize. Grindelia squarrosa appears to be increasing throughout its range and taking over areas that were occupied until recently by G. nana (and other species in other states)."