The endemic Onosma bracteosum Hausskn. & Bornm. (Boraginaceae) was investigated morphologically, anatomically and ecologically. It has setae with tuberculate bases. The stem is 15-35 cm tall and erect. The leaves are equifacial and amphistomatous. Stomata cells are anisocytic and anomocytic. The stomata index is 21.25 for the upper epidermis and 25 for the lower epidermis. This plant generally prefers sandy-loamy, sandy-clayey and loamy soils. In the soil samples, the N (23%). P (26%) and K (27%) concentrations were lower in the generative periods than in the vegetative periods. According to the results of plant nutrient anal ysis, N% (1.140-3.274), P% (0.172-0.403) and K% (0.512-1.281) concentrations are higher in the above-ground parts during the vegetative growth period. © Tübi̇tak.