Drymonia conchocalyx is a somewhat variable species that in all forms grows to very large size. This form had been distributed as the cultivar D. conchocalyx ‘Diane Marie’. The vining stems wind around trees and their branches in the forest, and in cultivation (necessarily in greenhouses) can also grow to substantial size.
The flower of this species is especially large — about 11 cm from the leaf axil to the end of the flower and about 4 cm across. The larger leaves in the image above are from the Drymonia, the smaller leaves are from a nearby Aeschynanthus.
This species is native to Nicaragua, Costa Rica and Panama.
Additional photos can be seen in a slideshow by clicking one of the links below.
Another plant with somewhat different flowers.