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.

Common Name: silver mock orange

Duration: Perennial

Nativity: Native

Lifeform: Shrub

General: Shrubs to 2 m tall with densely white pubescent twigs when young.

Leaves: Opposite, entire, ovate to elliptic oblong, 8-16 mm long, acute to obtuse at base and apex, appressed strigose on upper surface, whitish below.

Flowers: Solitary with the hypanthium and calyx appressed strigose, the sepals deltoid, about 5 mm long, corolla disciform, petals ovate, 6-10 mm long, 5-10 mm wide, the filaments distinct.

Fruits: Ellipsoidal and about 6 mm long.

Ecology: Found on rocky slopes and in canyon bottoms from 6,000-8,500 ft (1829-2591 m), flowers June-August.

Distribution: Ranges from Colorado to California, south to Texas, across southern New Mexico, and in Arizona.

Notes: There is a little uncertainty as to whether this is indeed a separate species. Some place this as a subspecies of P. microphyllus. We treat this as a separate species in line with Powell 1998, other authors have questioned whether any difference exists, suggesting that it is simply geographical variation in morphology among a single species. There has been no recent phylogenetic work on this genus to support either claim.

Ethnobotany: Specific use of the species unknown, however the genus was widely used to make spear tips and arrows.

Etymology: Philadelphus is a Greek-derived name after Ptolemy Philadelphus, Greek King of Egypt 309-247 BC, while argenteus means silvery.

Synonyms: Philadelphus microphyllus subsp. argenteus, Philadelphus microphyllus var. argenteus

Editor: SBuckley, 2011