A hybrid of two large-growing species, N. longipes and N. fritschii, N. 'Stoplight' is itself quite large-growing. It has a branching and spreading habit, with large, succulent leaves with decorative red backs. The very large flowers are produced on long pedicels, and dangle beneath the branches. I grew this plant hanging underneath flourescent lights -- it had been kept on the dry side, but watered and fertilized regularly. Almost fifty flowers were produced at one time.
Other Nematanthus with a similar dangling flower habit include N. crassfolius, N. corticola and N. brasiliensis.