Nematanthus crassifolius

Photo by John Boggan
Grown at the Smithsonian Institution greenhouses

Other Nematanthus with a similar dangling flower habit include N. 'Stoplight', N. fritschii N. corticola and N. brasiliensis.  A closeup of the flowers can be seen here.  A photo of a more recent collection with brightly colored calyces can be seen here.