Hoya siamica is a slender vine found in Thailand with long light green leaves. The leaves are on average 1.5-2 cm wide by 4-10 cm long. It has white flowers that come in clusters of 10 to 15. 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. The flowers are approximately 1.5 cm in diameter, fuzzy, have a slight scent, and last about a week when they flower during the summer.