Dendrobium helix is one of my favorite dendrobiums. The flowers can show a wide variety of colors, I have seen flowers that were bubble gum pink, others that were pastel yellow and the mahogany colored flowers of my own plant.
The two plants that I have seen in local collection and my own plant, have canes that are less than three feet tall, but the species is reputed to be able to produce canes up to six feet tall. The flowers last for months. The inflorescence in the photo is a tiny one, the plant can produce much larger ones.