[1] Vanilla siamensis is an evergreen climber that forms dark green shoots several meters long and[2] 0.4[3]–2[4] centimeters in diameter.

The leaves are oval, wedge-shaped at the base with a broad petiole 1.5–2.5 centimeters long.

[2] Vanilla siamensis is found in Yunnan province of southern China, Thailand, Cambodia, and Vietnam.

[5] It grows in evergreen forests at altitudes ranging from 700 to 1300 meters.

Vanilla pierrei, described by François Gagnepain on the basis of only one bud, is considered a synonym by Soto Arenas and Cribb.