Hoya siamica is a slender vine in the family Apocynaceae and tribe Marsdenieae; it can be found in Indochina and has characteristic long light green leaves.

The corolla of the flowers are white and flat; the corona can be a deep purple or a very pale yellow depending on how much light the plant receives.

[1] Hoya siamica was first found by Arthur Francis George Kerr and published by W. G. Craib in 1911 in the Kew Bulletin.

Kerr discovered the plant in the jungle on the mountain Doi Suthep which is near the city Chiang Mai, at an altitude of around 1500–1650 meters above sea level.

It was later also discovered in Gaoligongshan, Yunnan Province[2] and elsewhere in Indochina.