Erodium tataricum is a herbaceous perennial multi-headed tap-root (caudex) plant. Hemicryptophyte. Endemic. The ontogenetic structure was studied in the shrub-herb-grass petrophytic steppe. Individuals of the species have four periods and ten ontogenetic states. It was revealed that the population is normal with an incomplete spectrum. In accordance with the classification of A. A. Uranova and O. V. Smirnova the population is definitive. According to the criterion of the absolute maximum, the population is young. The ontogenetic spectrum of the population is left-sided. A specific ontogenetic spectrum corresponds to a characteristic ontogenetic spectrum, i.e. biology of the species. According to the ontogenetic spectrum, the development of the population is characterized as sustainable. The peculiarity of Erodium tataricum is that on all aerial parts of the plant there is abundant pubescence, but in the old generative ontogenetic state, pubescence on the leaves decreases. Reproduction of the species is carried out by seed. In the subsenile ontogenetic state, senile particulation is possible.