The Park flora is so rich and interesting that it has always been object of study.
It is possible to list on the whole about 2,000 species of superior plants, that is without considering musks, lichens, algae, and mushrooms.
Among the floristic peculiarities, Iris marsica stands out, an endemic species growing only in some locations and blooming between May and June. Moreover, there are several and multicolored orchids: the most beautiful, big, and rare is without a doubt the Yellow Lady's Slipper (Cypripedium calceolus), blooming in the most concealed corners between May and June.
Another rarity is represented by the Black Pine of Villetta Barrea (Pinus nigra), a relict species probably dating back to the Tertiary period; it is an exclusive variety of the Park which can be found in some areas of Camosciara and of Fondillo Valley. Among the spontaneous conifers there is the Swiss Mountain Pine (Pinus mugo), a glacial relict covering the vegetation strip between the beech tree wood and the high-mountain grassland, which can also be found mainly in the area of Camosciara.
However, the dominating vegetal landscape consists of beech tree forests: the scientific name of this species, Fagus syIvatica, recalls its spontaneous origin on the mountains of the Italian Apennines, where the presence of beech trees dates back to dozens of centuries ago.
As a matter of fact, the beech tree is the most common tree in the Park and generally grows between the 900 and the 1,800 meters of height. The beech tree woods cover more than 60% of the whole Park surface and concur in creating a landscape rich in colors, varying according to the season.
The high-mountain grasslands - which together with meadows and clearings cover more than 30% of the total Park surface - are typical of the upper part of the mountains and cover ridges and peaks around the 1,900-2,000 meters of altitude. Here vegetation mainly consists of various species of Gramineae and Cyperaceae, together with the yellow gentian and many other species during the warm season: gentian, gentianella, primerose, cyclamen, violet, anemone, scilla, lily, orchids, saxifrage, buttercup, woodruff, toothwort, ophrys, hellebore, liverwort.
Among the particularly showy flowers, there are the Fire Lily (Lilium bulbiferum croceum) typical of dry and sunny slopes, the Common Turk's Cap Lily (Lilium martagon) growing in the less thick beech tree woods, the Aquilegia ottonis, abundant in the grazing lands and in the uncultivated lands, the Gentiana dinarica, of an intense blue, and the above-mentioned Iris marsica.
The most famous flower of the Park is without a doubt the Yellow Lady's Slipper, a yellow and black orchid growing in the heart of the strict reserve, and relict of far epochs. This plant, also growing in Alpine locations, risks extinction because of the vandalistic and useless gathering by tourists; it is therefore necessary to adequately protect it. (Cypripedium calceolus)