This paper presents an analysis of the soil-plant relationships regarding the mobile forms of P and K in soil and their content in the herbaceous plant species (about 39 species belonging to 34 genera and 19 families) in 3 forest biocenoses of the European type from “Codrii” reserve. It was found that the studied soils, typical gray clay forest soils over clay-sandy loam and brown clay soils over deeply gleyed clay are secured with mobile P and exchangeable K, brown sandy loam soil over clay-sand shows lower values of P and optimum of K. Plants with a low P content (≤ 1 %, Bromopsis benekenii, Dactylis glomerata, Galeobdelon luteum) and high > 4 % P (Corydalis solida, Dentaria bulbifera, etc.); with K values within 3-10 %, species with narrow accumulation limits (Galium odorata, Convallaria majalis, Dentaria bulbifera etc.) and broader accumulation spectrum (Carex brevicolis, Carex pilosa, Melica uniflora, Dactylis glomerata, Euphorbia amigdaloides, Ficaria verna, Glechoma hirsuta, Viola Hirta etc ) were found.