romerillo

1 :  any of several tropical American plants with an aromatic odor most of which yield native remedies or dyes: such as a :  a South American herb (Heterothalamus brunioides) of the family Compositae whose flower heads yield a yellow dye b :  a Mexican shrubby milkweed (Asclepias linaria) that yields a violent purge c :  any of several Mexican plants of the family Compositae (especially Porophyllum scoparium and Chrysactinia mexicana)

2 :  the dye yielded by the South American herb romerillo