Abstract:The flowering phenology of Artemisia wudanica and A.halodendron were investigated at four levels (capitulum, inflorescence branches, individual and population) in the Horqin Sandy Land. The results showed that: (1) At the population level, the initial time of flowering of A.wudanica was 18th June, which was 9 d earlier than A.halodendron, the durations were 19 d and 16 d, respectively, and the overlapping flowering period was 10 d in two species. At the individual level, the initial time of flowering was 7 d earlier and the duration was 2 d longer in A.wudanica than in A.halodendron; (2)The number of capitulum on secondary inflorescence branches was less and duration was longer in A.wudanica than in A.halodendron. The flowering frequency of two species were all single-peak type, the highest frequency of flowering duration time at the secondary inflorescence branch were all 8 d, followed by 9 d; for the capitulum, the higher frequency were all 5 d, 4 d, 6 d and the highest one was 5 d; (3)The first flowering position was near the base of secondary inflorescence branches in A.halodendron, the highest frequency was the second and the third one from the base, being 12.7% and 11.9%, respectively. However, the capitulum on the top of secondary inflorescence branches was the first blossom in A.wudanica, the frequency was up to 56.3%; (4)The flowering amplitude curve of two species all showed a single peak curve, A.wudanica reached its peak on the 9th day after flowering, and A.halodendron was on the 6th day. The similarity of these two species’ flowering phenology reflected their phylogenetic relationship and adaptability to environment. The differences, especially the first flowering position, indicated the genetic differences in long-term evolution of two species.