EN
This paper analyzes the several reasons for variation in the endings of the fern name root in Baltic and Slavic. On the basis of etymology of Lith. 'papartis' (fern) it is possible to reinterpret the explanation of the word's semantic evolution provided by V. Maziulis (he postulates the presence of some sort of taboo, in order to separate the plant of the 'fern blossom (Farnblüte)' from the usual name 'fern'). The author concludes that: (1) the consonantal root structure of differing lexemes with the meaning 'fern' is determined by assimilation, not taboo; (2) the protosememe 'many wings/feathers on the ground' is reconstructed.