A new apiose-containing kaempferol trioside, kaempferol-3-O-α-L-rhamnosyl-(1‴ → 6″)-O-β-D-galactopyranosyl-7-O-β-D-apiofuranoside, along with 16 known compounds, were isolated from 50% acetone extract of Silphium perfoliatum L. Their structures were elucidated by acid hydrolysis and spectroscopic