The configuration of the terrain and geomorphological structure of the soil in Una National Park, the different elevation and the variety of flora are the conditions for the rich micro world that along with other forms of life contributes to the richness of biodiversity of Una National Park. In this area there are many rare and endemic species of plants: Gentian (Gentiana lutea), spotted gentian (Gentiana punctata), edelweiss (Leontopodium alpinum Cass) and juniperus (Pinus mugo). Una's bellflower (Campanilla unensis) is also an endemic species which is named after the river Una as well as Bosnian Iris (Iris reichenbachii Heuffel var. Bosniaca) that grows in a dry meadows and pastures on carbonate and serpentine rocks with shallow soil. Bosnian Iris is an endemic species from central and southeast Dinarides. Ecological conditions have enabled the development of a large number of diverse plant communities of exceptional value with over 1.900 plant species, which is 52,19% of all species present in Bosnia and Herzegovina. The area has recorded 177 official and 105 potentially medicinal, edible, of vitamin and aromatic plant species.
The area of the National Park is built of limestone cliffs inhabited by characteristic vegetation adapted to specific conditions of such characteristic habitats, like the cracking plants. Below the large rocky hills, under the influence of the hydrosphere and atmosphere, the parts of the rocks break off, roll down the slope, creating sporadic screes (sandbanks).
Weed and ruderal vegetation is related to all the settlements in this area. Thanks to a rural way of life, extensive farming and extensive livestock breeding, community classes Bidentetea, Artemisetea and Chenopodietea, are well developed. The diverse habitats abound in a large number of species and communities. In the area of the National Park, the exact number of species or communities cannot be assessed, but we can make a comparison with Austria, for example, which has recorded approximately 2000 species, while spatially small area of Una National Park, according to estimates, has more than 1000. In addition, there are many endemic species here and also relict - refuge communities, important not only for the immediate area, but also for the overall biological diversity of Europe. Therefore, it is expected that a large part of this area will be included in the NATURA 2000 - the Habitats Directive.