Following W, hyssopifolium is a widespread, variable southeastern species (2n = 20, 30) that includes var. calcaratum Fern. & Schub. (sometimes misnamed "E linearifolium Walt."), which is a narrow-leaved extreme (FNA 21). Colls. referred to var. hyssopifolium in its strict sense (F) appear to be intermediate between var. calcaratum and E. torreyanum, and mostly come from southeastern counties (BARR, LAUR, MCRE, PULA). A thorough review of colls. from Ky. is needed, partly to see if narrow-leaved plants have been spreading north during recent decades, as observed in Mo. (Y). The first records from Ky. that are referable to var. calcaratum date from the 1940s (M).