A sequential arsenic (As) extraction method using dil. HCl and 1:1 water-methanol was developed with approx. double the extraction efficiency (EE) of the current methods for terrestrial plants. Systematic study was conducted using the sequential method and many plant species sampled from an abandoned gold mining area at Deloro, Ontario. Total As in the plants studied ranged 1-500 µg.g-1. It was observed that all plants accumulated As up to the middle of growing season and a few continued accumulating until the end of season. Plants, without roots, overall contained the highest amounts of As in the leaves. Assimilation of As(V)/As(III) ratios in plants was independent of total As absorbed by plants. EE appeared to be inversely related to As(III) concentration in plants. Organic-As species was extracted more efficiently by 100% methanol. Different trend of EE for different plant species was observed. Plant extracts were analyzed by HPLC-HGAAS and HPLC-ICPMS; agreement of results showed that use of HPLC-HGAAS would be sufficient for speciation of As in plants grown on As contaminated soils. XANES analysis indicated seasonal variation in As species in plants.