Dendrobium polyanthum aka primulinum

This highly variable species is one of my favorite Dendrobium but it is a challenge to grow and bloom in the tropics because it is a plant native of a more temperate climate. The flower vary depending on its place of origin but they share a thing in common, the lip is huge and almost round. For the technically minded, the petiole of the flower is clavate. I saw this variation growing near the coast, so typically of this situation the plant had only a few flowers. The flower is just opened, they expand a bit after opening.

 

I varies in color, size and shape of the plant. The unifying principle is a round lip, but the lip can be white, white with purple venation, in plants from Laos it can have two yellow spots or a single large one, they can be nearly white to almost baby pink. The flowers are usually presented as single blooms on the sides of the cane. Here is my favorite plant. It is growing on the bottom of a plastic juice bottle. Here is a link where you can see my plant on full bloom.
Ricardo's Blog, : Dendrobium polyanthum Wall. ex Lindl. 1830 a rewarding species to grow