An experiment was established to study a population of long raceme peduncle-type (lp-type) lucerne. 15 groups of plants were grown in selection plots. Each group comprised plants originating from seeds collected from a single plant, and since lucerne is allogamous, the obtained results provided a basis for an evaluation within the maternal line. The aim of this study was to analyze the seed yield and the expression of phenotypic traits affecting the seed yield structure. Principle component analysis (PCA) was performed. The Euclidean distance and K-means grouping were used as a taxonomic measure of similarity between groups. Two agglomerated phenotypic groups were discriminated within the examined population, and the differentiating traits in a multivariate analysis were: number of racemes per shoot, number of seeds per shoot and seed yield per shoot. Statistical characteristics of the distinguished groups provided a basis for determining the ideotype with a high seed yield.