How are Obregonia and  Trichodiadema different from each other?
Obregonia Obregonia, the artichoke cactus, is a genus of cacti with a single species, Obregonia denegrii. The species is endemic to the state of Tamaulipas in Mexico.
Odontonema Odontonema, the toothedthreads, is a genus of flowering plants in the bear's breeches family, Acanthaceae. It is native to Central America.