Flora from the Maastrichtian era Nemegt Formation is spotty at best, but existing fossil evidence shows that there was some form of forest cover in the form of Pseudolarix conifers, with some hypothetical Baikalophyllum cycads and reedy plants thrown in the mix (known from similar localities in China and Russia).
Pott, C., McLoughlin, S., Lindström, A., Wu Shunqing, & Friis, E.M., 2012. "Baikalophyllum lobatum and Rehezamites anisolobus: two seed plants with “cycadophyte” foliage from the Early Cretaceous of eastern Asia." International Journal of Plant Sciences 173, 192–208.
Gradzinski, Ryszard. 1969. "SEDIMENTATION OF DINOSAUR-BEARING UPPER CRETACEOUS DEPOSITS OF THE NEMEGT BASIN, GOBI DESERT." Palaeontologia Polonica, No. 21, 148-223.
Okada, H. Cretaceous Environments of Asia (Developments in Palaeontology and Stratigraphy). Mateer, N.J. Elsevier Science, April 2000.