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Frangula obovata
 

 

Frangula obovata. Synonyms: Frangula betulifolia subspecies obovata, Rhamnus betulaefolia, Rhamnus betulifolia (Obovate Buckthorn)
Rhamnaceae (Buckthorn Family)

Semi-desert. Rock crevices. Spring.
Above: Butler Wash, Utah, May 21, 2014 and left, Canyonlands National Park, Utah, Confluence Trail, May 20, 2004.

Obovate Buckthorn often grows out of crevices in rocks otherwise bare of noticeable vegetation.  Such Buckthorns thrive on moisture and nutrients that filter through the porous sandstone.  In deeper soils of Canyon Country, Buckthorn typically grows three to five feet high and wide, twisting and drooping in an open pattern.  Given sandy conditions near a stream or at the base of rocks (as in the top photograph and the autumn photograph below), it grows to several inches in diameter and nine feet tall and wide.

"Rhamnos" is the classical Greek name for this genus, "obovata" refers to the sometimes reverse egg-shape of the leaves, and "betulifolia" means "Birch-like foliage".  Linnaeus named this genus in 1753, Edward Greene named the species in 1896, and Nesom and Sawyer renamed it in 2009.

From the description by Nesom and Sawyer:

Frangula betulifolia:   Leaf blades elliptic to oblong, elliptic-ovate, or narrowly ovate, 1.6–2.6(–2.9) times longer than wide, relatively thin or slightly thickened, paler beneath, lateral veins (8–)9–13 pairs.

Flowering Apr–Jun. Cliff bases, ledges, moist canyons, ridges, roadsides, rocky slopes, stream banks, Gambel’s oak, oak-pine, pine-walnut-maple, white fir; 900–2750 m. Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, Sonora, Tamaulipas).

Frangula obovata:  Leaf blades obovate to oblong-obovate or oblong, 1.2–1.8(–2.5) times longer than wide, distinctly thickened and nearly coriaceous, evenly colored on both surfaces, lateral veins (5–)6–8(–9) pairs.

Flowering Apr–Jun. Canyon bottoms, cliff faces, stream and creek banks, hanging gardens, talus, seepage below cliffs; 1350–2350 m. Ariz., Colo., Nev., Utah.  

The report (immediately above and in the map below) that Frangula obovata is found in Colorado is not supported by any collected specimens and is almost certainly in error.

Frangula obovata. Synonyms: Frangula betulifolia subspecies obovata, Rhamnus betulaefolia, Rhamnus betulifolia (Obovate Buckthorn)
Rhamnaceae (Buckthorn Family)

Semi-desert. Rock crevices. Spring.
Canyonlands National Park, Utah, May 20, 2004.
Corona Arch Trail, Utah, June 7, 2007.

Tiny yellow-white-green flowers are borne in leaf axles in mid-spring and then crisp little seed pods follow.

Frangula obovata. Synonyms: Frangula betulifolia subspecies obovata, Rhamnus betulaefolia, Rhamnus betulifolia (Obovate Buckthorn)
Rhamnaceae (Buckthorn Family)

Semi-desert. Rock crevices. Spring.
Upper Mule Canyon, Utah, October 23, 2006 and
Canyonlands National Park, Utah, November 11, 2005.

Autumn colors range from golds to lemons.

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

Frangula betulifolia

Range map for Frangula betulifolia

Frangula obovata

Range map for Frangula obovata