These were planted in the yard of the house where we stayed on Sanibel but the species was also seen here and there along roadsides and ditches elsewhere on the island. It was one of the few good butterfly plants we noted, attracting a few of the large skippers.

USDA PLANTS database now includes R. brittoniana (along with R. simplex) as a synonym of R. coerulea, while ITIS uses R. simplex for the other two taxa. Let's have an arm-wrestling match over this.
http://plants.usda.gov/core/profile?symbol=RUCA19
http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=832873