Its common names comes from populations on the La Panza Range, near the town of Santa Margarita. Arctostaphylos pilosula is a species of manzanita, known by the common names La Panza manzanita and Santa Margarita manzanita, that is endemic to California.
The plant is endemic to the La Panza Range and southern Santa Lucia Mountains, in the Central Coast region of California. It is found primarily in San Luis Obispo County. There is one occurrence in southern Monterey County.
It grows in chaparral and closed-cone pine forest habitatss, on shale outcrops and slopes. It is found at elevations of 30-1,250 metres (98-4,101 ft).
Arctostaphylos pilosula is an erect and bristly shrub growing 1-5 metres (3.3-16.4 ft) in height.
The leaves are a round, oval shape and dull and hairless in texture. They grow up to 3 centimetres (1.2 in) long.
The shrub blooms in spherical white inflorescences of cone-shaped and downward facing "manzanita" flowers, each just under 1 centimetre (0.39 in) long. Its bloom period is December to March.
The fruit is a reddish brown drupe about a centimeter wide, that ripen in the summer.
The species is listed on the California Native Plant Society Inventory of Rare and Endangered Plants as a fairly endangered and vulnerable species.