Sclerocactus cloveriae ssp. cloveriae (Not NMRPTC Rare)
[taxon report][distribution map][all photos][line drawing]
(Clover sclerocactus, Heil sclerocactus, Reeves sclerocactus)
Scientific Name: Sclerocactus cloveriae K.Heil ssp. cloveriae
Synonyms: Sclerocactus whipplei var. heilii Castetter, Pierce & Schwerin; Sclerocactus whipplei var. reevesii Casteter, Pierce, & Schwerin
Vernacular Name: Clover sclerocactus, Heil sclerocactus, Reeves sclerocactus
R-E-D Code: 1-1-2
Description: Hemispheric to columnar ribbed stem-succulent. Stems typically to 10 cm wide by 12 cm tall, sometimes larger. Ribs mostly 11 to 15, formed of coalescent tubercles. Areoles with upper portion elongated into short groove, often bearing sugar-producing glands. Spines usually about 11 in number, with four or five in a central position, uppers usually flattened and usually nearly white or sometimes pale yellowish, primary one usually terete and hooked apically and the lower two similar to the primary, but only rarely hooked. Lower three centrals typically brown to grayish fading to near white or pale yellowish apically. Radial spines usually about seven and primarily white, though two lower lateral ones often match lower centrals in color. Flowers born in spring from previous season's areoles at apex of stem. Flowers about 1.5 to 2.5 cm across when fully open but typically not opening widely, usually magenta to purple in color, but occasionally to nearly white or rarely pale purplish or rusty colored with yellow to orange overtones. Fruit green to brownish, pink, or pale magenta when mature, fleshy with soft walls, indehiscent, usually torn open by animals, but sometimes drying to a papery consistency when not disturbed. Seeds relatively large (approx. 2.5 mm) black or dark grayish, kidney-shaped with a lateral hilum.
Similar Species: Very closely similar to Sclerocactus whipplei, but that species is unknown in New Mexico. Sclerocactus whipplei is nearly an Arizona endemic, but occurs near Bluff, Utah. It should be looked for in New Mexico near the south west end of the Chuska Mountains. It differs from S. cloveriae in the seeds being slightly smoother and proportionately more broad and flattened, and in producing yellow flowers (very rarely with some purplish pigmentation on the Defiance Plateau).
Sclerocactus parviflorus is very common west and south of the range of S. cloveriae, but their ranges mostly do not overlap. Sclerocactus parviflorus is a larger plant with more spines at maturity; however, young plants are very like S. cloveriae. Distributions meet only on the north side of the San Juan River on the east base of the Hogback, and here the two species can be easily confused with one another. Flowers are produced about 2 to 3 weeks later in S. parviflorus under identical growing conditions, and are larger and open widely (typically over 2.5 cm, often to 5.5 cm in diameter when fully open). Flowers of S. parviflorus may be other colors. Sclerocactus parviflorus often has three or more hooked central spines, which is rare in S. cloveriae.
Also, see discussion under Sclerocactus cloveriae ssp. brackii.
Distribution: New Mexico, Rio Arriba, San Juan, and Sandoval counties; Colorado, La Plata and Archuleta counties
Habitat: Varied, nearly always in broken terrain on gravelly or rocky ground. Particularly favors slopes of river deposited gravels, but also on other substrates Associated vegetation is primarily desert grassland to open pinyon-juniper woodland, but also in big sagebrush scrub, shadscale desert, and ponderosa pine.
Remarks: This subspecies occurs from southern Colorado to southern Sandoval County, New Mexico, which is a distance slightly greater than 100 miles. It is relatively common within this range, thus it does not qualify as a New Mexico rare plant under NMRPTC criteria of either limited range or limited abundance.
Identification of species within the genus Sclerocactus has caused a great deal of confusion, and most species are confusingly alike. However, much work has been done on their taxonomy, and they are fairly well understood. Old and even recent literature often refers all New Mexico material to Sclerocactus whipplei, but that species has never actually been collected within the state.
Conservation Considerations: A very common species where it occurs, and nearly endemic to New Mexico. It is highly susceptible to disturbance of habitat. There are no immediate threats to the overall population, but locally agricultural uses and development destroy large numbers of plants. The species is desirable as an ornamental for rockeries, and is occasionally moved from habitat to yards nearby; however, it has never been collected on a commercial scale and collecting seem only a minor threat. Plants are short-lived, and often populations seem to die out completely due to insect attack, but this is a natural cycling of populations and is of no concern here.
Important Literature (*Illustration):
*Heil, K.D. and J.M. Porter. 1994. Sclerocactus (Cactaceae) a revision. Haseltonia 2:20-46.
Information Compiled By:
David J. Ferguson, 1998; last updated 2005