Five strains (Mizu2-1(T), Gon2-7, Koba6-1, Koyu2-2 and Miya2-2) of lactic acid bacteria (LAB) were isolated from flowers in Oze National Park, Japan, using anaerobic cultivation. The five isolates were found to share identical 16S rRNA gene sequences. The isolates exhibited low levels of 16S rRNA gene sequence similarity to known LAB; the closest recognized relatives of strain Mizu2-1(T) were the type strains of Lactobacillus kunkeei (94.9 %), Lactobacillus kefiri (94.1 %) and Lactobacillus buchneri (93.9 %). Comparative analyses of rpoA and pheS gene sequences demonstrated that the novel isolates did not show significant relationships to other Lactobacillus species. The strains were Gram-stain-positive, catalase-negative and heterofermentative. Anaerobic growth was better than aerobic growth. The isolates utilized a narrow range of carbohydrates as sources of carbon and energy, including glucose and fructose. On the basis of phenotypic characteristics and phylogenetic data, the isolates represent a novel species of the genus Lactobacillus, for which the name Lactobacillus ozensis sp. nov. is proposed. The type strain is Mizu2-1(T) ( = JCM 17196(T) = DSM 23829(T)).