On the territory of Belasitsa Nature park are found so far 1591 fern and seed plants, which represent around 39% of the flora of Bulgaria. The largest department, that of Flowering Plants (Magnoliophyta), contains 1554 species.
Among the rare plant we can mention  Ilex aquifolium L.  Taxus baccata L., Medicago carstiensis Jacq., Lilium albanicum Griseb., Viola stojanowii Beck., Viola speciosa Pant., Daphne kosaninii (Stoj.) Stoj., Epipactis exilis P. Delforge, Himantoglossum caprinum, Lathraea rhodopea Dingler and etc.
So far from the territory of the park we know about 146 species of mushrooms.
Very interesting are the ancient sweet chestnut forests which is rare habitat for Bulgaria and priority for conservation under the European Habitats Directive (92/43/ЕЕС). Chestnut forests in Belasitsa are different from those in north part on Balkan peninsula because of the mediterrenian elements presence such as Acer monspessulanum L., Platanus orientalis L., Colutea arborescens L., Coronilla emerus L., Periploca greaca L., Jasminium fruticans L.. This make them unique for Europe too.

Map of the region