here is the ground cover version of it. It gets covered with those flowers and keeps blooming entire growing season which is about 9-10 months in my area here is Ruela in the upright version, i have it in purple, white and pale pink. And last one is the compact version of mexican petunia unfortunately this pic was taken in late Feb or March bfr it had started blooming. All of them are prolific bloomers... so much for the mex petunia... but i don't think it's nicotiana either. How about giving a shout to @Iochroma?