Table 1.

List of various phytoremediation mechanisms and plant species used in various process.

Technique	Mechanism	Plant used	Plant parts	Surface medium	References
Phytoextraction	Uptake and accumulation of heavy metal into plant tissues with subsequent elimination of the plants	Brassica juncea Amaranthus hypochondriacus, Thlaspi caerulescens	Roots, Shoot, Leaves	Soils	Odoh et al., 2019; Cui et al., 2021; Singh et al., 2021
Phytodegradation/Rhizodegradation	Enzyme catalysed metabolism by rhizosphere-dwelling microorganisms to transform organic contaminant into simpler molecules	Rhizophora mangle, Salix viminalis, Vetiveria zizanioides, Typha latifolia	Roots, Leaves	Surface water, Groundwater	Sampaio et al., 2019; Papadopoulos and Zalidis, 2019; Nedjimi, 2021
Phytostabilization	Decreases the mobility and migration of soil contaminants	Atriplex undulata, Salix alba, Glebionis coronaria	Roots	Soils,Groundwater, Mine tailing	Mataruga et al., 2020; Li et al., 2021; Tammam et al., 2021
Rhizofiltration	Uptake of metals via plant roots	Eichhornia crassipes, Lemna minor, Pistia stratiotes	Roots	Surface water, Water pumped	Kodituwakku and Yatawara, 2020; Singh et al., 2021
Phytovolatilization	Removal of pollutants such as selenium, mercury, volatile hydrocarbons via evapotranspiration processes	Arundo donax, Stanleya pinnata, Brassica juncea, B. Napus	Roots, Leaves	Soils, Groundwater	Guarino et al., 2020; Hasanuzzaman et al., 2020; Yan et al., 2021
Phytostimulation	Phytostimulation (a symbiotic relationship that exists between plants and several soil microorganisms) is developed for the remediation of polychlorinated biphenyl (PCBs)	Brassica campestris, Zea mays, glycine max	Roots	Soils	Zahoor et al., 2017; Bilal et al., 2020