Alpine slopes in the highest areas (about 2.000 m.), are covered with a great variety of gramineous plants and colourful flowers, such as the Gentian flower, saffron, the carline thistle and the alpine pasque flower/alpine rose. Below this altitude there are woods of mountain pine (Pinus uncinata). Their underbrush is widely interspersed with juniper (Juniperus nana), rhododendron (Rhododendron ferrugineum) and bearberry (Arctostaphylos uva-ursi). The lower parts and the North-facing slopes of the mountain ranges are well populated with fir tree (Avies alba). Other forest species characteristic of humid zones and found in shady areas on the South-facing slopes is the beech tree (Fagus sylvatica), while the oak tree (Quercus pubescens) populates a good part of the sunny areas. These two species along with others are extensively interspersed in scotch pine's woods (Pinus sylvestris), which is mainly found in the medium and lower zones of the Park. Underbrush here is mainly comprised of rhododendron (Buxus sempervirens).