Abstract: In the distribution area, Jinchuan county, of Adenophora lobophylla Hong.population, 29 sample plots were investigated.The root system spatial structure and biomass of 1502 individuals with different ages were studied, and 5 populations at different altitudes were compared.The environmental factors which influence the root system development were analyzed too.The root system of the population at altitude of 2700-2900m could develop fully, the biomass and size of taproot, lateral root, secondary lateral root, thin root all reach the maximum.If the habitat is higher or lower than this altitude, the root systems of the population could not develop well.The most principal reason for the underdevelopment at the lower altitude was assumed to be drought and external extreme disturbance, and at the higher altitude was assumed to be low temperature.The relation between root system biomass growth(y, g) and ages(x, year) could be expressed by the equation:y=0.003783x^1.7953 for the whole population, and for the other 5 populations from altitude of 2300m to 3400m could be expressed by the general equation:y=a·x^b.

Key words: Adenophora lobophylla population, Root system growth, Biological characteristics, Biomass