Philadelphus microphyllus subsp. argenteus is an upper elevation shrub with small oval leaves which are pubescent mostly underneath. The leaves are broader than those of Fendlera rupicola, which it resembles. The four petals are oval and not spatulate as in Fendlera which has many fewer stamens per flower than does Philadelphus. Philadelphus microphyllus subsp. argenteus is found on dry, rocky slopes.