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

Click for more Sclerocactus photographs.

Click to see the Flora of North America key to Sclerocactus.

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

Intermountain Flora and Kartesz's Biota of North America consider Sclerocactus cloveriae to be a synonym for Sclerocactus parviflorus. They do not recognize Sclerocactus cloveriae as a species. But Flora Neomexicana III, Flora of North America, and Flora of the Four Corners Region do give S. cloveriae species status. However, the details about how to distinguish between S. cloveriae and S. parviflorus vary from flora to flora.

According to Flora Neomexicana III S. cloveriae has 4-9 central spines; S. parviflorus has mostly 4.
S. cloveriae has 2-8 radial spines; S. parviflorus has 6-17, "sometimes fewer".

According to the Flora of North America S. cloveriae has 6-9 central spines; S. parviflorus has (3-)4-6(-8).
S. cloveriae has 4-6 radial spines; S. parviflorus has 8-17.

According to Flora of the Four Corners Region S. cloveriae has 4-9 central spines; S. parviflorus has 4-6.
S. cloveriae has 2-8 radial spines; S. parviflorus has 3-17.

The FNA and the Flora of the Four Corners details were both written by Ken Heil and Mark Porter, the team that named and described S. cloveriae.

The FNA indicates, "Phylogenetic analyses of chloroplast DNA sequences support a close relationship among S. cloveriae, S. whipplei [yellow-flowering], and S. parviflorus (J. M. Porter et al. 2000)".

Bob Sivinski, New Mexico flora expert, believes that for distinguishing between S. cloveriae and S. parviflorus, "counting spines is fairly useless". He indicates, "The only way I can tell them apart is when they are in flower. Sclerocactus parviflorus has more elongate pointed flower buds and wider (2.5-5.5 cm) flowers. Sclerocactus cloverae has shorter more rounded buds and smaller (1.5-3 cm wide) flowers". Agreeing with Bob are the FNA flower measurements for S. parviflorus: (2-)3-5.7(-7) cm tall× 2.5-5.5(-8) cm wide and for Sclerocactus cloveriae: 2.5-3.5(-4) cm tall × 1.6-3.1(-3.6) cm wide.

The three floras mentioned above do agree that Sclerocactus cloveriae is a rare species of New Mexico and a few counties in southern Colorado (see map below) and that it is quite similar to Sclerocactus parviflorus and to Sclerocactus whipplei (a yellow-flowering species found in a few counties of northeastern Arizona and rarely in southeastern Utah).

Click to read more about S. cloveriae on the New Mexico Rare Plants website where you will note that S. cloveriae is divided by some botanists into two supspecies, S. cloveriae subsp. brackii and S. cloveriae subsp. cloveriae. Heil and Porter indicate that the two subspecies are distinguished from each other as follows:

S. cloveriae subsp. brackii has stems "mostly 3-7.5 cm long; central spines mostly 4(5), the lower often absent". Subspecies brackii is found only in San Juan, County New Mexico.

S. cloveriae subsp. cloveriae has stems "mostly 5-25 cm long; central spines mostly 8 (6-9), the lower hooked. Subspecies cloveriae is found from south of Albuquerque northward to very southern Colorado.

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

At the lower left of the flower at left and in the center of the photograph above, notice the new growth with several soft, red spines developing.

Sclerocactus cloveriae was named and described by Heil and Porter in 1994. "Cloveriae" honors University of Michigan botanist and explorer, Elzada Clover (1897-1980). (More biographical information about Clover). Steven Brack is a highly respected grower of Cacti and student of Sclerocactus and, with his wife Linda, owned Mesa Gardens Nursery in Belen, New Mexico for 40 years. (Read more about the Bracks.)

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

Sclerocactus glaucus has its troubles.  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 4th edition, Weber recants, saying that Sclerocactus glaucus is "rare on adobe soils, Colorado River valley", and he indicates that "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.

John Kartesz, ultimate authority for plant names on this website, indicates that this species is found in a few counties of Utah and a few in Colorado. See the range map below.

Whatever its species status is, S. glaucus is a very cute, 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.

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 (Mesa Verde Fishhook Cactus)
Cactaceae (Cactus Family)

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

Sclerocactus mesae-verdae is a minute, 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. Click for details about the biology of Sclerocactus mesae-verdae and the attempts to protect the species.

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

Sclerocactus mesae-verdae (Mesa Verde Fishhook Cactus)
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.