Sophora microphylla, S. prostrata and S. tetraptera are distinguishable from one another by their leaf flavonoids. S. microphylla is distinguished by the presence of rhamnosylvitexin and rhamnosylisovitexin and S. tetraptera by the presence of apigenin-7-O-rhamnosylglucoside-4'-O-glucoside and the 7-O-glucosides of apigenin, 7,4'-dihydroxyflavone, luteolin and 7,3',4'-trihydroxyflavone. Sophora prostrata lacks all these flavonoids, but has several pigments which are common to all three species.