Ali Botush (Bulgarian: Али ботуш), also spelled Alibotoush, is a nature reserve in the small mountain range of Slavyanka, located on the border between Bulgaria and Greece.

It was declared in 1951 to protect the largest forests of the endemic Bosnian pine (Pinus heldreichii) in the Balkan Peninsula.

[2] The reserve was created to protect the largest forests of Bosnian pine (Pinus heldreichii) in the Balkans and is renowned for its rich flora — over 1500 species found within its limited territory.

[4][5] The territory of Ali Botush has varied geomorphological forms and a number of ridges, such as Brezata, Saint Constantine, Mitnitsata, Tepleshki Peak and Chaplen Bair.

Ali Botush is home to diverse flora which has remain intact and pristine due to the reserve's relative isolation in the border zone.

On its tiny territory there are over 1500 species of vascular plants[2] which makes it a key floristic formation centre in the Balkan Peninsula.

The height of the individual trees can surpass 30 m. The beech and the fir grow in shady habitats with riches soils while the Bosnian pine occupies zones with less nutrients.

[8] Important protected species include the black maidenhair fern (Adiantum capillus-veneris), Polygala nicaeensis, Rhamnus fallax, as well as the Balkan endemic species Fritillaria drenovskii, restricted to Slavyanka, Pirin and northern Greece,[9] Pulsatilla rhodopaea, Saxifraga siribrnyi, long-spur violet (Viola delphinantha),[2] restricted to this area of Bulgaria, as well as Greece,[10] Paril centaurea (Centaurea parilica), restricted to Slavyanka and southern Pirin,[11] etc.

In 2012 one of the world's rarest fungi, Zeus olympius, known until then only from Mount Olympus in Greece, was discovered in Ali Botush.