The characters of population density

capitulum number

seed production and 1 000seed weight about Parthenium weed under different environments including crop land

grazing land

sparse forest and roadside were studied in this paper. The results showed that the characters above all of Parthenium weed under different environments were various. The population density ranged from（10±2）~（80±24）/m2

capitulum number ranged from（2 618±843）~(14 539±3 296)/m2

seed percentage range from (43.8±5.6)%~(82.5±2.2)%

seed production ranged from（10 308±1 036）~（60 361±14 661）/m2

1 000seed weight ranged from (0.34±0.06〖DK〗)~〖DK〗(0.46±0.01) g. To the population along the roadside

the density was the maximum while seed percentage and 1 000seed weight was the minimum. In vitro

to the population distributed in crop land and sparse forest

the density was the minimum while seed percentage and 1 000seed weight was the maximum. The invasive ability and adaptation of

Parthenium hysterophorus

to environment were discussed in this paper according to reproductive characters.