Abstract:The changes of Cynodon dactylon propagules under flooding were studied in morphology and biomass. Results showed that the stem length increased with increasing of flooding depth, whereas leaf number decreased obviously. Flooding duration had significant effects on leaf number, stem diameter, and ratio of stem length to root depth, but not on branch number, stem length, root depth, stem node number. The aboveground biomass and total biomass of plants decreased significantly with the prolongation of flooding time, but the underground biomass of plants changed little. Plants of all the treatments could survive and recovered after flooding. However, stem length, root depth, branch number, stem diameter, leaf number, leaf length, leaf width and ratio of leaf length to leaf width all decreased significantly with the increase of flooding duration during recovery, so did the stem, leaf, root biomass and total biomass. But node number and leaf number of plants showed no significant difference among treatments. It suggested that Cynodon dactylon had strong toleration to flooding by prolonging stem, changing leaf shape and reducing biomass.