Abstract: In this study, Lappula semiglabra, an ephemeral plant species and the most sensitive to water conditions in the Ebinur Lake Wetland Nature Reserve, Xinjiang, northwest China, was selected as the research object. Three condensed water gradients, i.e., the group T1 without cover, group T2 treated with semi-covered and group T3 treated with complete cover, were designed. The purposes of the study were to lucubrate the effects of condensed water on the plant height, canopy size, leaf area, leaf thickness, root length, root diameter, leaf relative water content, leaf water potential and biomass allocation of L.semiglabra plant. The results showed that: ① In the late plant growth season, the plant height, canopy size, leaf area, leaf thickness, leaf relative water content, net photosynthetic rate, stomatal conductance and leaf water potential were significantly increased (P<0.05) with the increase of condensed water; on the contrary, there was no significant difference of root length and root diameter among the 3 treatments (P>0.05); ② The stem mass ratio (SMR) was relatively stable in the biomass allocation, and it varied in a range of 3.0%-13.5%. The difference of leaf mass ratio (LMR) among plants was significant (P<0.05), the root mass ratio (RMR) decreased gradually, but there was no significant difference. It could be concluded that the leaves of L.semiglabra in arid area can absorb and utilize condensed water. The morphological characters are highly sensitive to water and have high variability.

Key words: desert region, ephemeral plant, Lappula semiglabra, condensed water, Ebinur Lake, Xinjiang