When Hoya pubicalyx ‘Black Dragon’ came on the scene a few years ago it was touted as a true black flower.  It was much over hyped in my opinion; most blooms were nowhere near black in color and were not as nice as many of the standard varieties that had been grown for years.  I gave my plant up a couple of years ago for lack of space, but I kept my old Hoya pubicalyx ‘Royal Hawaiian Purple’ standby and I’m glad that I did. Look at how dark some of these flowers are!  These are completely not retouched and they look even darker in person than in the photos.