Острица, Nature reserve in Pernik Province, Bulgaria.

Ostritsa is a maintained botanical reserve on the slopes of Ostritsa Peak in the Golo Bardo mountain, within the lands of Pernik, Radomir and Kralevo Dol. The peak is built mainly of limestone, and the reserve holds rock formations, landslides and stone screes; its southern slopes are almost entirely covered with rock, while flora is well developed elsewhere. About 300 higher plant species have been recorded, over 250 of them herbaceous.

The area was protected in 1961 to preserve the natural habitats of the region. This early decision made it one of Bulgaria's older protected areas.

The reserve's name comes from Ostritsa Peak, whose limestone slopes it protects. Its grassland species represent three continents: Europe, Asia and Africa. Among them are Bulgarian endemics such as the Urum tulip, Urum mullein and Bulgarian pink, and Balkan endemics including Reichenbach's iris and globe yellow gentian.

The reserve lies on the slopes of Ostritsa Peak in the Golo Bardo mountain, split between the lands of Pernik, Radomir and Kralevo Dol. The southern slopes are almost entirely bare limestone rock with scree and rockfalls, so approach from the more vegetated northern parts. The protected area covers 1,359.88 decares, reduced from 1,363 decares by order RD-41 of 19 January 2015.

Ostritsa is a botanical reserve, not a birdwatching site: about 300 higher plant species have been recorded here, over 250 of them grasses. Grasses typical of three continents — Europe, Asia and Africa — grow on the slopes of Ostritsa Peak, including the Bulgarian endemics Urum's tulip, Urum's mullein and Bulgarian pink.