Phyllostegia glabra is a species of flowering plant in the mint family known by the common name ulihi phyllostegia. It is endemic to Hawaii. One variety of this species, var. lanaiensis, is federally listed as an endangered species of the United States. It is a perennial herb with reddish or red-veined green leaves and white or white-tinged flowers. It differs from the variety glabra in the size of its sepals and leaves. The rare variety lanaiensis has not been seen since a single specimen was recorded on Lanai in the 1980s. It may still exist on the island, perhaps in rugged habitat that has not been surveyed recently.