The [3+2] cycloaddition reaction between nitroolefins and alkyl/aryl azides was studied using functionalized silver nanoparticles (FnAgNPs) of average diameter 23 +/- A 1 nm as catalyst produced by the plant extract Protorhus longifolia. We found FnAgNPs to catalyze the reactions efficiently yielding a series of 1,5-disubstituted-1,2,3-triazolines under mild reaction conditions with no side products. The catalytic activity of FnAgNPs was compared with naked AgNPs and FnAgNPs found to be very effective. Except solvents, the whole experiments do not require any chemical/reagent which makes the process green. [GRAPHICS]