Hoya tsangii was first collected by Daniel Edward Elmer in August of 1912. He found it in the Philippines, Mindanao Island, Agusan del Norte, Cabadbaran (Mt Urdaneta). Unfortunately, he labeled it incorrectly as Hoya angustifolia an invalid name. This was only the beginning of the confusion with the taxonomy of this species. At one time or another it has been called Hoya burtoniae, Hoya odetteae, and Hoya sp. aff. burtoniae. These are all incorrect; this plant belonging to the Acanthostemma Section of Hoya, with the little yellow flowers, is now definitively known Hoya tsangii. A big shout out to Mary Caroll for providing me with much of this research!