It's not easy to find a new plant for the USA-especially when it is a small herbaceous thing that grows among wetland vegetation.  Not only do you have to know the plants that frequent the area but you have to spot differences from known look-a-likes. 

In this case Everglades National Park had a known population of Cuphea carthagenensis but we felt that "our " plant was different (smaller leaves, nearly devoid of hairy bristles on stem and calyx, shorter leaf petioles, less branching and far fewer flowers, etc).  We checked the Fairchild Tropical Garden Herbarium which contained some additional species of Cuphea but none seemed to be a fit.

Next, at the recommendation of friends, we sent a sample to Dr. Daniel Ward of The University of Florida for his opinion.  He thought that it was Cuphea carthagenensis but communication remained open.

A few years and letters later we learned that Dr. Shirley Graham of Kent State University, an authority on the genus Cuphea, declared "our" plant to be Cuphea strigulosa and "the first collection and report of it in the States...."  "It occurs in western and eastern South America (Peru, Ecuador, Colombia, Bahia to Rio de Janeiro in Brazil) and in scattered places in the Caribbean (Dominica, Puerto Rico...)" to quote Dr. Graham further.

To the left is a photo of Cuphea strigulosa as it grows among wetland grasses and sedges in Everglades National Park.