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Mat Rockspirea (Petrophyton caespitosum)
Perennial Forbs Around Las Vegas, Vegetation Around Las Vegas
Mat Rockspirea (Petrophyton caespitosum)

General: Mat Rockspirea or Rock Mat (Petrophyton caespitosum) is a perennial forb that grows as a dense mat over the surfaces of bare rocks. Club-like clusters of flowers are held on short stalks above the evergreen leaves. Individual flowers are typical for the Rose family, but the club-like clusters are unusual.

Mat Rockspirea is an uncommon component of vegetation communities in dry, well-drained rock (limestone) surfaces in the mountains of the Upper Sonoran (Pinyon-Juniper Woodland), Transition (Yellow Pine Forest), Canadian (Pine-Fir Forest), and Hudsonian (Bristlecone Forest) life zones.

Family: Rose (Rosaceae).

Other Names: Rock mat, rock spirea.

Mat Rockspirea (Petrophyton caespitosum)

Plant Form: Prostrate, perennial forb. Considered a subshrub because of the woody base.

Height: leaves to an inch or so, flowering stalks to 2-3 inches.

Stems: Prostrate.

Leaves: Evergreen, crowded together, entire, somewhat triangular.

Flowers: Blooms early summer. Inflorescence: spike. Flowers: petals white, tiny (1.5 mm); to about 40 tiny stamens. Spikes dry to a reddish-brown.

Mat Rockspirea (Petrophyton caespitosum)

Seeds:

Habitat: Dry limestone rock surfaces in the mountains.

Elevation: About 4,000 to 10,000 feet.

Distribution: Southwestern U.S.

Comments:

Mat Rockspirea (Petrophyton caespitosum) Mat Rockspirea (Petrophyton caespitosum)
Mat Rockspirea (Petrophyton caespitosum) Mat Rockspirea (Petrophyton caespitosum)
Mat Rockspirea (Petrophyton caespitosum)
A mat of leaves
Mat Rockspirea (Petrophyton caespitosum)
Leaves
Mat Rockspirea (Petrophyton caespitosum) Mat Rockspirea (Petrophyton caespitosum)
Mat Rockspirea (Petrophyton caespitosum)
Leaves
Mat Rockspirea (Petrophyton caespitosum)
Individual leaves: upper = dorsal surface, lower = lower surface
Mat Rockspirea (Petrophyton caespitosum)
Flowers
Mat Rockspirea (Petrophyton caespitosum)
Flowers
Mat Rockspirea (Petrophyton caespitosum)
Two stems with open flowers and one stem with flower buds
Mat Rockspirea (Petrophyton caespitosum)
flower buds
Mat Rockspirea (Petrophyton caespitosum)
flower buds
Mat Rockspirea (Petrophyton caespitosum)
flower buds
Mat Rockspirea (Petrophyton caespitosum)
Opening flowers
Mat Rockspirea (Petrophyton caespitosum)
Opening flowers
Mat Rockspirea (Petrophyton caespitosum)
Open flowers
Mat Rockspirea (Petrophyton caespitosum)
Open flowers
Mat Rockspirea (Petrophyton caespitosum)
Open flowers
Mat Rockspirea (Petrophyton caespitosum)
Several individual flowers

Note: All distances, elevations, and other facts are approximate. Names generally follow the USDA database.
copyright; Last updated 240908

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