This annual, or perhaps biennial, is widely scattered across eastern North America (K), but usually restricted to remnants of native grassland on seasonally damp base-rich soils (Shenk & Holsinger 2001). It is a hemiparasite, with wide range of herbaceous host plants (Malcolm 1962). Across its range: "Populations of C. coccinea seem ephemeral, disappearing from one site after a few years and appearing in another" (FNA 17). And for the genus as a whole, FNA 17 noted: "Many species of Castilleja decline when grazed by domestic livestock, especially on islands... Plants are damaged both by cropping of inflorescences and by trampling of the often brittle stems. Removal of grazing pressures usually results in recovery of the affected populations... A number of Castilleja species contain alkaloids, including some assimilated from parasitized hosts via haustorial bridges... Some species of Castilleja are reported to absorb and concentrate selenium, producing potentially toxic effects in grazing animals." Within Ky. the only known secure populations (with 100s-1000s plants) are in rocky glades of LARU and LEWI, and in an old cemetery of ROCK that is mowed annually in mid- to late-May before Memorial Day (J. Hays, pers. comm.). C. coccinea is a variable species, with reported 2n = 24, 46 and 48. FNA 17 noted that it "usually has red bracts. Forms with white or yellow bracts have been named but are scattered across the range of the species. However, yellow-bracted forms become markedly more common in populations in the northern portion of the range, especially in the upper midwestern region." Presumably referring to a paler form, Short (1840) reported "Euchroma pallida, barrens of Kentucky; much less abundant than E. coccinea." C. pallida (L.) Spregel is a species of western Canada and Alaska. The closely related diploid (2n = 24) perennial of more western regions, C. sessiliflora Pursh, was reported from Ky. by BA in error (M).