Abstract: Tengger Desert has a complex flora with a rich species composition and as it is located in the transitional zone between desert and grassland in central Asia. Based on a large number of site investigations, and reference to relevant plant and specimen databases and literature, we catalogued the spermatophytic flora and species geographical distribution categories in Tengger Desert through application of the basic principles of floristic geography. We found that the spermatophytic flora of Tengger Desert fitted in the middle transitional zone of Northwest China, and had the characteristics of a typical desert flora, including 382 natural spermatophytic species, belonging to 201 genera and 60 families. Floristic dominance was obvious in Tengger Desert where the floristic species tended to be concentrated in dominant families with more than 10 species, accounting for 64.40% of all the species. Floristic plants were highly differentiated, and there were as many as 178 genera represented by single species and oligos, accounting for 88.56% of all the genera. The Tengger desert flora contained a complex mix of genera from 14 global distribution categories and a further 9 sub-categories, including among others: cosmopolitan (40 genera), pantropic distributed (19 genera) and north temperate distributed (26 genera). The proportion of genera of temperate origin was 44.78%, which indicated the typical temperate zone characteristics of the Tengger Desert flora. Genera of paleo-mediterranean origin were also an important influence, comprising 21.39%, of the flora. The family representation was dominated by types with world distribution, including 38 globally widespread families. The proportions of globally dominant and representative families present in the Tengger Desert were 77.78% and 40.00%, respectively, which is consistent with the harsh desert climate in the region. The tropical component comprised 11 families, accounting for 18.33% of all the families, which showed that the flora of Tengger Desert has tropical links. However, the floristic origin of Tengger Desert was ancient and contained some new evolutionary forms, including primitive families of polycarpous plants, as well as some ancient relic species and many types with discontinuous distribution. In addition, there were relatively young and evolving families. Overall, the data indicate a very complex origin of the Tengger Desert flora.

Key words: desert flora, dominant family, representative family, floristic geographical composition, Tengger Desert