chpter 1. According to the report by Environment Protection Administration, the fifth level of heavy metals polluted soil area in Taiwan was approximately 1046 ha in 2002. these heavy metals include Cd, Cu, Cr, Pb, Zn, Ni, Hg and As. Cadmium (Cd) is a non-essential toxic element, and widely use for engineering and chemical industry. The organisms take up the Cd and transfer through food chain to accumulate finally in human body. The environmental consciousness raise recently, contaminated environment was remediated by natural way, such as phytomediation. In the recent year, several terrestrial plants and macrophytes have been reported to bioaccumulate heavy metals. After accumulation in plants, Cd2+ can have considerable detrimental effects on the absorption and transportation of essential elements, metabolism, growth and reproduction. The aim of the present study was to explore the possibility for using Canna indica Linn. and several ferns in phytoremediation scheme for reducing Cd level of environment. Chapter 2. Cd is an industrial and environmental pollutant. Canna indica Linn. seeds were germinated in 0, 1, 2, 4, 10, 50, and 100 mg L-1 doses of CdCl2. Results showed that Cd did not affect the seed germination, but root number and root length was affected by high Cd concentration treatments. Cd has toxic effects on root tip growth and morphogenesis of C. indica Linn. The root tip was brown at high CdCl2 concentration. Cd induced morphological changes such as no root cap, cell vacuolization. Effects of Cd on growth and photosynthesis of C. indica L. were studied. C. indica was cultured in 1/2 strength Hoagland’s nutrient medium, which was supplemented with 0, 1, 2 and 4 mg L-1 of CdCl2 and harvested after 7, 14, 21, and 120 days. The Fv/ Fm of CdCl2 treatment was significant different from that of control, however, the value was remain 0.81 to 0.82. The processes affected by Cd in C. indica Linn. leaves were photosynthesis rate, transpiration rate and stomatal conductance, but of intercellular CO2 concentration was not affected except 4 mg L-1 CdCl2 treatment. This study showed that Cd affected on plant biomass accumulation and leaf chlorosis were observed. The Cd concentration in leaf, stem and root increased with initial concentration and also with passage of time. Plants treated with 4 mg L-1 CdCl2 the accumulated highest content of Cd in root after 120 days. The maximum values of bioconcentration factor (BCF) was 1632.3 of root by 1 mg L-1 CdCl2 treatment, suggested C. indica Linn. was a accumulator of Cd could be treat environment contaminated with low Cd concentration. Chapter 3. The effects of CdCl2 concentration on spore germination, prothallium development, and sporophyte of Pteris fauriei Hieron, Phymatodes scolopendria (Burm) Ching, Aglaomorpha meyeniana Scott, Diplazium maoneouse Ching and Asplenium nidus L. were studied. The spore germination was inhibited above 20 mg L-1 CdCl2, and there was no significant difference between control and 2 mg L-1 except P. fauriei Hieron. Cd delayed the antheridia formation besides P. fauriei Hieron. Fv/ Fm was decreased at high CdCl2 treatment as an indictor of Cd stress. The toxic symptoms of frond were chlorosis, red-brown and defoliation from joints. Cd affected the frond growth and biomass accumulated even at low CdCl2 concentration. Plants at high CdCl2 accumulated higher Cd concentration, and mainly in roots. The maximum bioaccumulation factor value was 452.3 of P. fauriei Hieron., indicated it was a low accumulator. Salvinia molesta Mitchell and Azolla pinnata R. Brown were tested in variation pH of CdCl2 concentration solutions. Plants at more acid solution were higher Cd uptake than plants at low acid solution.