(a–g) Production of Au NPs by the roots of the live plants: (a) Phyllanthus fraternus, (b) Portulaca grandiflora, (c) Cicer arietinum, (d) Medicago sativa, (e) Euphorbia hirta, (f) Amaranthus gracilis and (g) Vernonia cinerea. The plants were exposed to 0.0, 0.5, 1.0 and 2.0 mM HAuCl4 aqueous solutions. Some controls contain the culture medium supplemented with cationic gold but not the plant. Adapted from Ref. [60] permission from the Royal Society of Chemistry (RSC). (h–k) Localization of Ag NP within the plant tissues of Brassica juncea: (a) leaf, (b) lower section of outer stem, (c) root and (d) lower section of inner stem. Adapted from Ref. [61] with permission from the RSC.