Slovenian teacher, botanist and mineralogist who originally studied theology and became a catholic priest (1795) but gave it up due to poor health. Hladnik became schoolmaster at a number of schools in Laibach for almost 40 years until his sight failed. Laibach was the former capital of the Austrian province of Carniola, and during the Napoleonic Wars became part of the French Illyrian provinces. The occupying authorities gave Hladnik the post of Professor of Botany and Natural History in the Central School of Laibach and sufficient land to found a garden (1810). After Bonaparte's defeat Laibach was returned to Austria when the European Congress determined Europe's national borders (1815) but later passed to Yugoslavia (1819) and is now Ljubljana, the capital of Slovenia.

Hladnik was to spend some 30 years collecting the indigenous flora of Carniola and displaying it at what would become the Ljubljana Botanical Garden. He bequested his herbarium to the Rudolfinum Public Museum, which had been recently founded in 1831, and is now the Slovenian Museum of Natural History or Prirodoslovni Muzej Slovenije (LJM). In 1819 he discovered a rare Slovenian endemic in the Apiaceae which was named Hladnikia Rchb. (1831) in his honour by Ludwig Reichenbach at Vienna. Undated material collected by Hladnik of H. pastinacifolia from Reichenbach's exsiccatae is at BM. Several other species have also been named after him.