Two new putative hybrid species of Poa, P. navashinii Nosov and P. levitskyi Nosov are described and illustrated. They were found in the southeastern Altai Mountains (southern Siberia, Russia), on a riverbank and in dry mountain steppe. Both of them resemble the species of sect. Stenopoa (a xerophytic group) but have some traits that suggest hybridization with species of other sections, presumably sect. Poa or Malacanthae. Intersectional reticulation with formation of new taxa occurs in mountain regions though species of the sect. Poa s. stricto and sect. Stenopoa cross rather rarely. Our data add support to a significant role of hybridization in the phylogeny of Poa and the Poeae tribe in general.