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     The Sclerocactus genus was named by Nathaniel Britton and Joseph Rose in 1922.  "Sclero" is Greek for "hard".   

      Click for more Sclerocactus photographs.

Sclerocactus glaucus
Sclerocactus glaucus
Cactaceae (Cactus Family)

Foothills. Gravels, sandy openings. Spring.
Near Delta, May 22, 2007.

Sclerocactus glaucus has a difficult life.  Utah and Colorado plant experts Stanley Welsh (4th edition of A Utah Flora) and William Weber (3rd edition of Colorado Flora Western Slope) don't even believe in it.  Welsh lists it as a variety of Sclerocactus whipplei (which some Cactus experts believe Welsh misidentifies -- see S. parviflorus below). 

In his third edition of Colorado Flora: Western Slope William Weber says that Sclerocactus glaucus is "perhaps only a variant of [Sclerocactus whipplei]" which he indicates exists in Colorado. In his 2012 4th edition, Weber says Sclerocactus glaucus is "rare on adobe soils, Colorado River valley". (And he indicates, "S. whipplei apparently does not reach Colorado".)

The Flora of North America gives Sclerocactus glaucus species status and indicates that it is found only in the vicinity of Grand Junction, Delta, and Montrose, Colorado.

S. glaucus is a very small plant (one to four inches tall) and difficult to locate.  Flowers are pink and fragrant.

"Glaucus" is Greek for "gray or bluish gray" and is used botanically to describe a gray/white waxy coating (similar to that on a plum).  The species was at first named Echinocactus glaucus by Schumann in 1898 and was given its present name by Cactus expert Lyman Benson in 1966.

Sclerocactus glaucus
Sclerocactus glaucus
Cactaceae (Cactus Family)

Foothills. Gravels, sandy openings. Spring.
Near Delta, May 22, 2007.

The number of spines per areole, their color and minimal curvature, their length, and their shape in cross section are all key in identifying Sclerocactus glaucus. 

Sclerocactus mesae-verdae
Sclerocactus mesae-verdae
Cactaceae (Cactus Family)

Semi-desert. Shrublands, sandy openings. Spring.
New Mexico, April 24, 2007.

Sclerocactus mesae-verdae is a minute, lovely, rare Cactus found only in Colorado and New Mexico in a very small area near Mesa Verde National Park.  It is very difficult to locate because it is so rare and so minute, but when it is found it usually occurs in groupings of several dozens.  Flowers range from creamy pink to creamy yellow. 

Sclerocactus mesae-verdae is a federally endangered species, and for the past several decades its populations have been very closely monitored.  Off-road vehicles, housing development, gas and oil development, and collectors threaten to annihilate this lovely plant.

Boissevain discovered and named this species Coloradoa mesae-verdae in 1940 and it was renamed by L. Benson.

Sclerocactus mesae-verdae
Sclerocactus mesae-verdae
Cactaceae (Cactus Family)

Semi-desert. Shrublands, sandy openings. Spring.
New Mexico, April 24, 2007.

Spines radiate in a starburst; central spines are not always present but when they are, they may be hooked.

Click for more Sclerocactus photographs.

Sclerocactus parviflorus
Sclerocactus parviflorus subspecies intermedius
Cactaceae (Cactus Family)

Semi-desert. Woodlands, openings. Spring.
Corona Arch Trail, Utah, April 13, 2005.

Sclerocactus parviflorus is up to a foot and a half tall (but typically four to seven inches tall), round (up to six inches in diameter, but typically three or four inches), ribbed, and its spines radiate in a beautiful starburst.  In the photograph at left, the red spines below the flower buds are soft, new spring growth.  Older spines are quite stiff and sharp and the longest spines usually are hooked.  Young plants are half buried in the soil.  Plants are usually solitary, not in the large groupings common for Opuntia.

According to the Flora of North America, flowers range from soft pink to satin violet-pink to white or rarely yellow.  I have only seen the satin violet-pink flowers in Colorado and Utah.

The species was named by Elzada Clover and Mary Jotter in 1941 from their collection in the Glenn Canyon area in 1940.  The plant is found through northern Arizona, northwestern New Mexico, far southwestern Colorado, and central and southern Utah.   

"Parviflorus" is Latin for "small-flowered", not a very appropriate name for this large-flowered plant.

This plant formerly appeared on this web site under the name Sclerocactus whipplei but an email to me by Cactus expert Dorde Woodruff alerted me to the fact that S. whipplei occurs only in northeast Arizona and around Bluff, Utah.  Some botanists maintain that S. whipplei has a larger range and contains many subspecies spread across Utah.  The authoritative Flora of North America agrees with Ms. Woodruff's assessment.

The FNA also indicates: "Sclerocactus parviflorus has an extensive range and great morphologic variation.  Many named segregates have been proposed (L. D. Benson 1982; K. D. Heil and J. M. Porter 1994; F. Hochstätter 1995b) and some of these clearly merit recognition at the subspecific or varietal level.  However, we are not attempting to subdivide this very complex group. Considerable work remains in understanding morphologic diversification within this species."

Sclerocactus parviflorus
Sclerocactus parviflorus subspecies intermedius
Cactaceae (Cactus Family)

Semi-desert. Woodlands, openings. Spring.
Corona Arch Trail, Utah, April 13, 2005.

Click for more Sclerocactus photographs.

Sclerocactus parviflorus
Sclerocactus parviflorus subspecies parviflorus.  Synonym: Sclerocactus cloveriae.
Cactaceae (Cactus Family)

Semi-desert. Shrublands, sandy openings. Spring.
BLM Land South of Bloomfield, New Mexico, April 24, 2007.

Sclerocactus parviflorus subspecies parviflorus (formerly considered Sclerocactus cloveriae) is a rare subspecies of New Mexico and a few counties in southern Colorado.  It is quite similar to Sclerocactus whipplei and Sclerocactus parviflorus subspecies intermedius but it is generally smaller and more rounded, growing perhaps to four inches wide and five inches tall.  The arrangement, shape, and number of spines is also diagnostic.  Notice the new growth with several soft, red spines developing immediately in front of the two flower buds.

"Cloveriae" honors University of Michigan botanist and explorer, Elzada Clover (1897-1980).  (More biographical information about Clover.)

Sclerocactus parviflorus
Sclerocactus parviflorus subspecies parviflorus.  Synonym: Sclerocactus cloveriae.
Cactaceae (Cactus Family)

Semi-desert. Shrublands, sandy openings. Spring.
BLM Land South of Bloomfield, New Mexico, April 24, 2007.

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 Sclerocactus glaucus

Range map for Sclerocactus mesae-verdae

Range map for Sclerocactus parviflorus

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