Dendrobium polyanthum aka Dendrobium primulinum var. Laos, the flowers of two different clones.

About a decade ago there was a large importation of plants of Dendrobium polyanthum to the island of Puerto Rico, in fact they also seem to have been sold in the United States.  Some ot these plants have survived and bloomed.  The top photo is a flower from a plant that I grew from a keiki.  The flower has a large yellow area in the labellum.  The bottom flower is from a plant that I brought as an adult, the area of yellow is smaller than in the flower on top but the labellum is larger.  The plant that produced the flower on top is a slow deliberate grower that is somewhat delicate, the plant that produced the flower on the bottom is a vigorous grower and blooms relatively well.