Assisted phytoremediation is extremely promising, but is still in development and needs fur-ther study. Therefore, the combination use ofErythrostemon gilliesiiand humic acid wasstudied to aid the efficiency of lead nitrate Pb(NO3)2phytoextraction. Seedlings wereexposed to five simultaneous treatments of Pb(NO3)2(0, 100, 300, 500, and 700mg L1)andhumic acid (0 and 300mg L1) for three growth months (90days in summer) and theireffects on physiological and morphological traits of plants were recorded. Up to 300mgL1, Pb treatments showed apparent positive (stimulative) effects on plant traits, includingdry and fresh weight, length, number of leaves, the diameter of collar and root, and rootgermination. Lead treatments higher than 300mg L1showed negative (repressive) effectson plant growth. A decrease in Pb uptake was observed in simultaneous treatments ofhumic acid and Pb, which means more Pb remains unabsorbed in the soil. We concludethatE. gilliesiiis well-suited to the phytoextraction of Pb in contaminated areas, but humidacid significantly reduces the efficiency of remediation; therefore, the levels of humic acidshould be controlled during the remediation process in an area
