Kadua st-johnii (formerly Hedyotis st-johnii) is a rare species of flowering plant in the coffee family known by the common name Nā Pali beach starviolet. It is endemic to Hawaii, where it is known only from the Nā Pali coast of Kauai. It is a federally listed endangered species of the United States. This is a succulent perennial herb with squared stems that trail along the ground. The leaves are fleshy and mostly concentrated low on the stem. The flowers are borne in clusters. Each has a tubular corolla of green petals.