This is a hybrid of what is now known as Sinningia douglasii, although the other species involved is not known for sure. There is some suggestion in the accompanying text that it might be Gesneria discolor, now known as Sinningia gigantifolia. A print of S. douglasii can be seen here, a photo of the species here.
While this is not a double-wide print, the landscape orientation is used effectively to provide a larger-than-normal image. It is particularly nice in that the overall habit of the plant is illustrated in the engraving to the left, and the leaf in the background. The print of S. douglasii is similarily structure, and was printed in the same edition of Van Houtte’s Flore des Serres et des Jardins.