Origin and Habitat: Grusonia parishiiSN|9896]]SN|9896]] is found in the United States, within the Mojave and Sonoran Deserts of southeastern California, northwestern and southern Arizona, and southern Nevada. The range is disjunct with the subpopulations in Nevada and California being well-separated from the Arizona subpopulations.
Altitude range: 900 to 1,200 metres above sea level.
Habitat and Ecology: Mojave and Sonoran deserts. Grusonia parishiiSN|9896]]SN|9896]] can be found in scattered patches within valleys on silty or sandy soils, as well as in gravelly plains in the desert. This species also grows on dunelets, and basaltic rock hillsides. It grows in Larrea tridentata shrubland with other cactus species where it form mats which are almost indistinguishable from the dry bunch grass in which it is frequently found. Though much alive, the joints appear most of the year to be wholly dead. The rapidly growing young shoots present an array of brilliant red spines contrasting with the dull colour of the older growth. Drifting sand usually partially covers the old, prostrate joints. This is a widespread and very abundant species with a very big population. There are no major threats (although there are some concerns about the California subpopulations)

• Grusonia parishii (Orcutt) Pinkava
• Corynopuntia parishii (Orcutt) F.M.Knuth
• Corynopuntia parishiorum (Orcutt) F.M.Knuth
• Corynopuntia stanlyi var. parishii (Orcutt) Backeb.
• Opuntia parishii Orcutt
• Opuntia stanlyi var. parishii (Orcutt) L.D.Benson

Description: Grusonia parishiiSN|9896]]SN|9896]] (Corynopuntia parishiiSN|9898]]SN|9898]]), is a low, much branched plant, that grows in spreading mats or clumps along the sandy ground. The stems are short, 10-20 centimeters tall, produce roots along the undersides, and grow outward from the initial point to form broad clusters and mats up to 2 (or more) metres in diameter. The segments are up to 9 cm long by 3 wide and surfaced in fleshy tubercles hidden under a dense armament of angled, strongly flattened spines each up to 5 centimeters in length. Young spines are red or pinkish, but soon becoming grey and finally white, blending remarkably with the short, dry desert grass in natural camouflage. The flower is pale lemon-yellow, fading to salmon and the fruit is yellow and up to 8 centimeters long. A characteristic plant that could not be mistaken for any other species in the region.
Stems: 10-20 cm in series of usually 1-2 stem segments, from fibrous roots. Segments more or less obovoid, gradually narrowed basally and club shaped, basal to terminal about 5-9 cm, 2-3 cm diameter. Tubercles separate,12-25 mm long, 3-8 mm high wide, 4-6 times longer than wide.
Areoles: Round, c.5 mm in diameter, with grey to white wool. Glochids yellow, 5-8 mm long.
Spines: 14-22, woody, mostly borne on upper areoles or uniformly distributed over entire segment, grey to brown, with yellowish tips. Largest apical spines about 5, diverging, somewhat round, angular and flattened basally,, to 42 mm long. Central spine brown or white, long tapered. Main basal spines 5-6, whitish to pinkish to tan, strongly bent backward, flattened, 25-45(-58) mm long margin white, thick, sheath separating only at tip.
Flowers: Inner perianth 1.5-2.5 cm long, pale yellow with narrow reddish midribs, 1.5-2.2 cm long. Filaments pinkish or green. Style whitish to pale yellow or dull pinkish; stigma lobes white, greenish white or pale yellow.
Blooming season: Late spring-early summer. The blossoms remain open only about two hours.
Fruits: club-shaped , with a deep umbilicus at the summit, 3.5- 5.5(-8) cm long, 1.5-2 cm in diameter, fleshy, yellow; usually not spiny or only weakly so but completely covered with dense radially arranged yellow glochids.
Seeds: 3-4.5 mm.
Chromosome number: 2n = 22.
Taxonomic Notes: This species has been described as Grusonia parishiiSN|9896]]SN|9896]] by Pinkava (1999). Crook and Mottram (2001) indicated that the species epithet "parishii" was an orthographic error as it was named jointly after S.B. and W.F. Parish, hence the name should to be corrected to parishiorum.

Bibliography: Major references and further lectures
1) Wikipedia contributors. "Grusonia parishii." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 15 Mar. 2015. Web. 15 Mar. 2016.
2) Anderson, E.F. “The Cactus Family”. Timber Press, Portland. 2001
3) Crook, R. and Mottram, R. “Opuntia Index. Part 7: nomenclatural note and P-Q.” 19: 91-116. 2001
4) Pinkava, D.J. “Cactaceae cactus family: part three. Cylindropuntia (Engelm.) Knuth, chollas.” Journal of the Arizona - Nevavada Academy of Science 32(1): 32-47.1999
5) Puente, R. & Baker, M. 2013. Corynopuntia parishiorum. The IUCN Red List of Threatened Species 2013: e.T152673A664152. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T152673A664152.en. Downloaded on 15 March 2016.
6) Unknown,“Grusonia parishii” in Flora of North America @ efloras.org <http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242415179> FNA Vol. 4 Page 119, 122, 123 accessed on 15 March 2016
7) Bruce G. Baldwin, Douglas Goldman, David J Keil, Robert Patterson, Thomas J. Rosatti “The Digital Jepson Manual: Vascular Plants of California” University of California Press, 07 February 2012
8) “Bradleya: Yearbook of the British Cactus and Succulent Society”, Volumes 18-21 The Society, 2000
9) Lyman D. Benson “The Native Cacti of California” Stanford University Press, 01 September 1988
10) Ira Waddell Clokey “Flora of the Charleston Mountains, Clark County, Nevada” University of California Press, 1951
11) Elmer Yale Dawson “The Cacti of California” University of California Press, 1966
12) Desert Botanical Garden (Ariz.), “Science Bulletin”, Editions 1-4 Arizona Cactus and Native Flora Society
13) Edmund Carroll Jaeger “Desert Wild Flowers” Stanford University Press, 1940

Cultivation and Propagation: Grusonia parishiiSN|9896]]SN|9896]] is a a much decorative hardy cactus seldom found in cultivation. It is a summer grower species that offers no cultivation difficulties. Its cylindrical densely spiny joints provide a striking accent for an otherwise dormant cactus garden.
Soil: Use a very a particularly draining substratum, as it is sensitive to rottenness when in presence of humidity and low temperatures and let the soil dry out between waterings, since it's natural habitat is in sandy or gravelly, well draining soils.
Repotting: Repot in the spring, when their roots become cramped. Generally, they should be repotted every other year in order to provide fresh soil. After repotting, do not water for a week or more.
Water: In summer, during the vegetative period, it must be regularly watered, but allowing the substratum to completely dry up before irrigating again (but do not overwater ); in winter, it’s to be kept dry. Preferable not to water on overcast days, humid days or cold winter days.
Hardiness: It is a quite frost resistant cactus, hardy to -7° C if very dry. However in cultivation it is better not to expose it to temperatures lower than -0° C, even if in an aerated and protected location, in order to avoid the formation of anti-aesthetic spots on the epidermis. In presence of high atmospheric humidity avoid any frost as it is particularly sensitive to root rot. It can handle extremely high temperatures in summer.
Exposure: Outside full sun or afternoon shade, inside needs bright light, and some direct sun.
Use: It is suitable for “desert” gardens, in association with other xerophytes. Where the open air cultivation is not possible due to the climate, it is to be cultivated in pot in order to shelter it in winter.
Warning: It is armed with treacherous spines that are extremely sharp (This is one of the most dangerous of all cactus). Handle it with extreme caution, and keep it away from gangways and areas frequented by children and animals. Spines must be meticulously removed with tweezers.
Propagation: Stem division. Prickly pear pads root easily and grow rapidly when placed in loose, well-draining soil.