In this paper, AgNO3 (silver nitrate) solution was used as liquid elec
trode to accelerate the growth of water trees in polyethylene. It was
found that water trees grown in AgNO3 solution can be colored spontane
ously during their formation, their areas are brownish-yellow, and the
y grow fast. Scanning electron microscopy (SEM) revealed microchannels
in the AgNO3-grown water tree with diameters from 0.2 to 0.5 mu m. In
fact,these microchannels are possibly filled with metallic silver red
uced from silver ions, and these water trees are referred to as 'silve
r trees'. The structure of the silver trees is studied and analyzed in
comparison with sulfide trees and blue water trees. The effects of si
lver ions (Ag+) in the silver tree region are investigated and a compa
rison is made with other ions such as KS, Na+, Mg++, and Cu++ in water
trees. The trees from AgNO3 solution grow much faster than trees from
the other solutions. Finally, the mechanism of the formation of silve
r trees is suggested.