While working over the Russian variant of the common 'Etymological Dictionary of the Slavic Languages. Common Slavic lexical stock' (EDSL) its compilers were gradually coming to the conclusion that in the common Slavic language there existed the lexical-semantic group of names of trees, bushes and grasses containing the collectivity suffix -ar', where r' stands for soft variant of consonant r, namely: *b7tar' , where 7 stands for reduced back vowel, (weed(s)), *kustar' (bush), *leshchar' (hazel), *lipar' (lime forest), *listar' (foliage) and some other. Quite a few facts from the North Slavic region have already been given in the materials of the EDSL: *b7tar' - also Russian (dialectal), *kustar' - exclusively Russian and Belorussian (dialectal in both cases), *listar' - also Russian (dialectal). Besides isolated examples also continuous area of sought-for formation use speak in favour of the common Slavic version. Compare the map of the old grass names in 'Lexical Atlas of Belorussian dialects' (V 1 1993 Nr 278), where the contradistinction of the forms 'vish' and 'vishar' takes place. The latter of the forms is localized to the east and the west of the former, that is in theoretically more archaic regions. Nevertheless, the weightiest argument serving as evidence of just common Slavic character of the collectivity suffix -ar' is the presence of its correspondence in Baltic languages. As far back as 1913, K. Buga pointed out that dendronyms 'bérzas' (birch) and 'liepa' (lime) gave names to the lake 'Bérzoras' and two villages 'Lieporai', Lithuania. The author got the clue to the interpretation of the pointed out forms created from dendronyms when he paid attention to the fact that under 1331 one and the same mountain in Prussia had two word-formative variants of the name: 'Leypiten' and 'Lepare'. Cf. in modern Lithuanian collectivity suffix -yte and actually registered appellative 'liepyte' (lime bushes). Hence, we have the names of two Lithuanian villages 'Lieporai' as well as Balto South Slavic lexicalword-formative isoglottic line Lith. 'Lieporai' – Serb. 'lipar' (lime grove).