Foothills. Roadsides, woodlands, openings. Summer.
Dolores River Overlook, July 14, 2004.

Petradoria pumila is a very common plant found in extensive colonies lining trails and roads and filling meadows.  It first attracts attention to itself in early summer with bright green, dense, six inch diameter clusters of vertical leaves.  Then, in mid-summer (when this photograph was taken), its four-to ten inch stems are topped with a mass of tiny, attractive, golden/yellow flowers. The base of the plant often has a whorl of gray dead leaves from the previous year’s growth. This whorl could be confused with the very similar whorl of Stenotus armerioides.  Petradoria pumila is also confused with Gutierrezia sarothrae but the latter usually blooms later in August and September and is taller, woody, bright yellow, in more rounded clusters with very narrow, short leaves.

"Petra" is from the Greek for "rock: and "doria," is, according to William Weber, "an old name for a Goldenrod".  "Pumila" is Latin for "dwarf".

A specimen of this plant was first collected for science by Thomas Nuttall "in open situations on shelving rocks" in the Rockies (Intermountain Flora).  Nuttall named the plant Chrysoma pumila in 1841 and Edwin Greene renamed it Petradoria pumila in 1895.  This is the only species in the Petradoria genus, but see the discussion below about whether this species has two varieties.

Foothills. Roadsides, woodlands, openings. Summer.
Dolores River Overlook, July 26, 2009.

Foothills. Roadsides, woodlands, openings. Summer.
Lone Mesa State Park, July 14, 2011.

These clumps of Petradoria are very unusual.  In fact, I have never seen anything like them, for Petradoria pumila commonly grows in small clusters to about six inches in diameter.  These robust clusters are 15-24 inches in diameter.  Leaves are very narrow and flowers are few in each head.  These characteristics led me to think that these plants are Petradoria pumila variety graminea. But after researching the graminea variety and after examining these plants closely, I just am not sure what these photographs show. 

For a good discussion of the possible differences between Petradoria pumila variety pumila and variety graminea, read Tom Chester.  His conclusion is very reasonable: we are dealing with gradations within a species, not separate varieties.

Petradoria pumila (Rock Goldenrod)
Asteraceae (Sunflower Family)  

Foothills. Roadsides, woodlands, openings. Summer.
Lone Mesa State Park, July 14, 2011.

Petradoria pumila (Rock Goldenrod)
Asteraceae (Sunflower Family)  

Foothills. Roadsides, woodlands, openings. Summer.
Lone Mesa State Park, July 14, 2011.

Petradoria pumila (Rock Goldenrod)
Asteraceae (Sunflower Family)  

Foothills. Roadsides, woodlands, openings. Summer.
Lone Mesa State Park, July 14, 2011.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Petradoria pumila