purple-

These are Opuntias with purple pads when stressed or in winter. Not all specimens have purple pads and it is important to grow the right clone.

Opuntia chlorotica gosseliniana

Opuntia chlorotica gosseliniana
Opuntia chlorotica gosseliniana

(Weber) Ferguson, Cactus and Succulent Journal (U.S.) 60: 159, 1988

Isotype; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium

Original Description

What is Opuntia chlorotica gosseliniana?

O. chlorotica gosseliniana is one of three varieties along with vars chlorotica and santa-rita within the O. chlorotica complex as described by Ferguson (1988). The three types blend into each other over their range where they overlap. 

Details

These prickly pear cacti may reach 1 m tall (usually shorter), and are almost always tinted with pink or purple or bluish purple. Like O. chlorotica chlorotica, O. chlorotica gosseliniana has needle-like spines on older trunks and branches. Unlike O. chlorotica chlorotica, O. chlorotica gosseliniana can form multiple ascending branches. This Opuntia variety may have spines in most areoles, only in upper areoles, or in none at all.  The slender spines vary from relatively short and stiff to long and flexible, up to 10 cm.  Additionally, the spine color varies from cream to bright yellow and through shades of orange- and reddish-brown to nearly black. 

Flowers are generally yellow from bluntly pointed buds. The stigma lobes are generally pale. Flowers are 5-7.5 cm across. Fruit is elliptical to cylindrical. This variety has smaller and relatively more slender fruit than vars chlorotica and santa-rita.

O. chlorotica gosseliniana is diploid. 

Other Notes

This prickly pear is native to Mexico, and it barely reaches into the United States in far southern Arizona on land of the Tohono O’odham Nation. Thus, is is not commonly encountered.  The garden plant often sold as O. santa-rita ‘Tubac’ may actually be a horticultural selection of O. chloritica gosselliniana. 

Opuntia mojavensis

Opuntia mojavensis
Opuntia mojavensis

Engelmann & Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 293, 1856

Lectotype; Herbarium (O. mojavensis-like); Herbarium (O. mojavensis-like); Herbarium (O. mojavensis-like); Drawing (The Botany of the Expedition, 1856)

Original Description

What is Opuntia mojavensis?

Opuntia mojavensis is an enigmatic prickly pear cactus. The only  historical drawing of this cactus shows 2 spine clusters and an immature or sterile fruit. The herbarium sheet (lectotype) for this prickly pear also has limited material. It is found at elevation at the summit of Mt. Potosi in southern Nevada and in similar places westward. 

Details

O. mojavensis forms woody-stiff plants sprawling to 2 m across. O. mojavensis has distinctly angular branches caused by its woody nature as well as sometimes-rising branches. Cladodes are irregular in size but often obovate. The spines seem similar to those of the lectotype as well as in the drawing above. However, spination is irregular and there are 0-2(5) spines per areole, even on the same pad. Plants may turn a pleasing red-purple color in winter. 

Flowers are 5-8 cm across and yellow with distinct or light red centers, green stigmas, and yellow anthers. Outer tepals may be tinged with red or red-orange. Fruit is reddish and may be barrel-shaped. 

Ploidy is unknown. 

Other Notes

We observed a population of plants growing at the summit of Mt Potosi (Highway 160 summit) near Las Vegas, Nevada that we interpret be O. mojavensis. We base our description of the taxon on that population and on similar plants found further west mostly in the trans-montane regions of California. The original location (mountains above Victorville/Hesperia, California) matches the Mt Potosi location in general terms of plant companions and altitude but is about 150 miles west of Mt. Potosi. Thus, we envision O.  mojavensis as a species of high elevations west of Arizona and across the Mojave Desert into the mountains of southern California. Though it is obviously a desert plant, we have seen the taxon at Big Bear Lake in California. 

Because of its attractive  flowers, angular growth shape, and obvious cold hardiness, O. mojavensis would be interesting in a garden. However, it is a large sprawling plant. 

Opuntia chlorotica santa-rita

Griffiths & Hare, New Mexico Agricultural Experiment Station Bulletin 60: 64, 1906

Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium

Opuntia chlorotica santa-rita
Opuntia chlorotica santa-rita

Original Description

What is Opuntia chlorotica santa-rita?

Opuntia chlorotica santa-rita is one of three varieties of the prickly pear cactus,  Opuntia chlorotica. The varieties are santa-rita, gosseliniana, and chlorotica (Ferguson 1988). Santa-rita is the most handsome. The three varieties blend into each other over their range where they overlap. 

Details

O. chlorotica santa-rita is an upright, open-branching cactus to 1.5 m with a distinct trunk (sometimes two trunks) up to 15 cm across. The cladodes are suborbicular, orbicular, or rarely obovate or even pointed. Cladodes are about 12 to 18 cm across with a bluish or purplish cast. Some individuals are strongly colored. Spines are absent in this Opuntia, or there may be 1(3) per in a few areoles at the tips of the cladodes. If spines are present they are yellow to reddish-brown or sometimes darker, and 2-3 cm long. 

Britton and Rose described the flowers of this Opuntia as very handsome, deep yellow, and 6 to 9 cm across. The filaments and style are white, and the stigma is white or yellow.  The fruit is oval and depressed at the apex; it is purple outwardly and greenish within and pleasant to taste. 

O. chlorotica santa-rita is diploid.

Other Details

Britton and Rose reported that the type locality of this Opuntia is the Celero Mts [Salero Mt?] of AZ. It was also described from the Santa Rita Mountains. Britton and Rose also reported that, “All gradations of spine characters may be found between this and the typical, very spiny Opuntia chlorotica.”

O. chlorotica santa-rita is a sumptuous and large garden plant. Its coloration alone makes it valuable, and the large, colorful flowers are a bonus. Cold-hardiness seems likely to be moderate (USDA climate zone 6?). 

Opuntia macrocentra

Opuntia macrocentra
Opuntia macrocentra

Engelmann, Proceedings of the American Academy of Arts and Sciences 3: 292, 1856 [1857]

Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium (as O. violaceae macrocentra); Herbarium (as O. violaceae macrocentra); Herbarium (O. macrocentra minor); Herbarium (O. macrocentra minor); Herbarium (O. macrocentra minor)

Original Description

What is Opuntia macrocentra?

Opuntia macrocentra is a much-grown and much-enjoyed prickly pear cactus found in western gardens. It is related to O. azurea. The flowers are attractive and the pads are often bluish or are purple. 

Details

From Powell and Weedin:

O. macrocentra plants are spreading to upright plants, 30-60 cm tall or taller. Cladodes are obovate to orbicular, 10-20 × 10-20 cm, or the pads are slightly wider than long. Spines may be produced on the upper one-fourth of the pad or only in the areoles of the upper edge. Occasionally, plants may be essentially spineless. The largest spines are often directed upwards. Spines are black to reddish-brown and 5-10 cm long. 

Flowers have sharply defined, bright red centers that may be star shaped. They are 6-8 cm long and 5.5-8 cm wide. The filaments are about 1.5 cm, pale green proximally and cream-colored distally. Anthers are yellow. The style is cream-colored and 1.7-2 cm long. The stigma lobes are cream-colored or pale green. The reddish fruit is oboviod, ovoid, or ellipsoid, 3-4.3 cm long, 1.5-3 cm in diameter, and deeply concave. The rind is purple and the juice and pulp are pale-purple to clear. Seeds are flattened, tan, 3.4-4.5 mm in diameter, 1.5-1.9 mm thick with a broad notch on one side and a prominent raphae. 

O. macrocentra is tetraploid

O. macrocentra minor has been described by Powell and Weedin, and it is diploid. 

Other Notes

O. macrocentra has been confused with O. chlorotica santa-rita and O. azurea, but the three cacti are distinct. It is unfortunate that O. macrocentra was sometimes mislabeled as a prickly pear variety of O. violaceae because O. violaceae is a nonexistent species.

Britton and Rose reported that specimens with bluish pads can be especially showy.

O. macrocentra is an excellent garden plant in many climates. Its striking color and beautiful flowers are impressive. It is easy to grow in USDA climate zone 7 and warmer if the climate is not to wet. Plants can become large in gardens and without drought stress may not reach their best stress-caused color. 

Opuntia gilvescens

Opuntia gilvescens
Opuntia gilvescens

Griffiths, Annual Report of the Missouri Botanical Garden 20: 87, 1909

Holotype (as O. gilvescens); Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium;  Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium. Except where indicated, all specimens  were originally interpreted as O. phaeacantha. 

O. gilvescens is related to O. camanchica

O. gilvescens is related to O. phaeacantha

Original Description

What is Opuntia gilvescens?

Opuntia gilvescens is a widespread, medium-sized cactus. It occurs from Oklahoma all the way to and southern Nevada and desert California. It is a common plant in Arizona. It is often confused with O. phaeacantha, in part because there is no slot for it in most guidebooks. 

Details

O. gilvescens has nearly round or obovate cladodes that are generally dull. Main branches rest upon the ground and other branches rise to 30-80 cm. O. gilvescens is often a symmetrical plant. Mature plants may be 1 m across. Cladodes  may be 20 × 25 cm, but they are often smaller. Spines are not numerous, and there may only be 2 major spines; but there may be 1-4 on first-year growth. The tips of spines are translucent. 

Many O. gilvescens flowers have a blush of red at the bases of the interior tepals, but some individuals may have rust-colored veining that can darken or spread as the flower ages. Cacti with all-yellow flowers may be found. Also, some cacti have pink flowers as in parts of southern Utah. Stigmas are green, pale green, or yellow-green. Anthers are yellow or cream-colored. Filaments are yellow but can darken towards the base. Fruit is round-bottomed or barrel shaped, but may occasionally have a narrow base, ripening to pink, reddish, or even greenish-pink. Flesh is greenish or pink-green, sometimes dark. Seeds are about 0.75 cm across with a 1 mm rim.

O. gilvescens is hexaploid.

Other Notes

The authors have found this prickly pear in Oklahoma (Arbuckle Mountains and west), in western  and central Texas, in many parts of New Mexico as well as in Arizona, southern portions of  Nevada, Utah, and Colorado, and in the mountains of the eastern California Mojave Desert. Similar-appearing prickly pears have been found in the mountains east of Palm Springs, California. Additionally the plant occurs in the Chihuahuan Desert of Mexico. 

Plants from southwest New Mexico and adjacent Arizona are often pale; sometimes they have rhombic or more elongate joints and pale spines. Plants from the Mojave Desert area often have round pads with fewer than average areoles and a few pale spines. Plants from the Chihuahuan Desert of Mexico and into central Texas are often dark in appearance; they may become strongly red-purple in winter and the spines can be black.

In central New Mexico, O. gilvescens fits the type description well. Some southern populations, such as populations on the east side of the Sandia Mountains and down into Socorro County, and again in the Alamogordo area, often have wide, curved pads creating an interesting potato chip look.

Opuntia charlestonensis

Opuntia charlestonensis
Opuntia charlestonensis

Clokey, Madrono 7(3): 71, 1943

Isotype; Isotype; Isotype; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium

Original Description

What is Opuntia charlestonensis?

Opuntia charlestonensis is a prickly pear cactus that occurs from about 6,000 to 8,000 ft in Kyle Canyon on Mt Charleston, Nevada. It is proposed to be a hybrid taxon derived from two species, O. phaeacantha and O. polyacantha erinacea.

Details

Plants may be 20 to 40 cm tall and up to 1.5 m across. They are generally prostrate, but short branches of a few cladodes may arise from prostrate main branches. Cladodes are oval or obovate and 10-20 cm long and 7-14 cm wide. Cladodes may be strongly purple in the winter and spring. Spines (4-6) are light in color, and spreading in all directions.

O. charlestonensis has yellow or canary-yellow flowers that darken late on the day of anthesis; there may be a blush of red in the flower centers. Flowers are 4-5 cm across. Stamens and anthers are yellow as is the style and stigma. However, the style may be tinged with red. Fruit is oval and dull reddish-purple with a green pulp. Seeds are flat and 4-5 mm in diameter.

O. charlestonensis is pentaploid.

Other Notes

O. charlestonensis is sympatric with the two proposed parental Opuntia species, but O. dulcis also grows in Kyle canyon. This latter Opuntia has not been investigated as a possible parent. 

This prickly pear was originally (1943) only known from Kyle Canyon on Mt. Charleston, NV. However, in 2014 a population of this Opuntia was reported in CA where it also seems to be formed by hybridization. 

Opuntia basilaris

Opuntia basilaris ramosa
Opuntia basilaris ramosa

Engelmann & Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 298, 1856

 

Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Holotype (O. basilaris brachyclada); Herbarium (O.  basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris longiareolata); Herbarium (O. basilaris longiareolata) Herbarium (O. basilaris longiareolata); Herbarium (O. basilaris longiareolata); Isolectotype (O. basilaris ramosa);  Herbaraium (O. basilaris ramosa); Herbarium (O. basilaris heilii); Herbarium (O. basilaris heilii); Herbarium (O. basilaris heilii); Isolectotype (O. basilaris woodburyi); Holotype (O. humistrata); Herbarium (O. basilaris treleasii); Holotype (O. basilaris whitneyana); Painting; Painting; Painting

Original Description

What is Opuntia basilaris?

Opuntia basilaris is a distinctive prickly pear cactus; it has the archetypical “beaver tail” look. Mature plants form dense clumps 15-30 cm tall and 30-100 cm across. The pads are blue-green or grayish-green and are often wedge shaped or broadly obovate. Pads are (7)15-17(22) cm long.

Details

Often the cladodes of this prickly pear are fan shaped, but they may be oval, obovate or even elongate-obovate. The pads of the major variety of this Opuntia (var basilaris) arise from a single point and form an approximate rosette. The areoles are slightly sunken. This prickly pear has blue-green or gray-green pads that are distinctive and that may have hints of purple, or they may be entirely purple under stress. Though spineless, there are numerous small glochids to be avoided.

Flowers are magenta and about 7-8 cm across, very showy. Fruit is dry. They style is white or pinkish-white, and the stigma is  white. Filaments are red, anthers are yellow. The seeds are large and thick (subspheric?) and angular. They measure 6.5-9 × 6.5-7 mm.

O. basilaris basilaris is diploid, but O. basilaris treleasei is triploid.

Other Notes

We recognize five varieties of this Opuntia:

  • basilaris
  • brachyclada
  • longiareolata
  • ramosa
  • treleasei

Britton and Rose discuss several varieties that are not recognized here including: albiflora, coerulea, and nanna. O. basilaris basilaris is by far the most commonly encountered variety. All varieties of this  prickly pear are spineless except var treleasei. 

Native Americans used O. basilaris as a medicinal plant (Anderson, 2001). Perhaps there was some beneficial effect to ingesting the cactus because it contains 3,4-dimethoxyphenethylamine, a compound related to dopamine and mescaline. 

O. basilaris is a favorite in gardens because of its unique shape, pad colors, and bright flowers. Some clones from higher altitudes are cold-hardy. 

Opuntia azurea

Opuntia azurea
Opuntia azurea

Rose, Contributions from the U.S. National Herbarium 12(7): 291, 1909

Holotype; Isotype; Isotype; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium (O. azurea diplopurpurea); Holotype; (O. azurea diplopurpurea); Holotype (O. azurea discolor); Herbarium (O. azurea discolor); Herbarium (O. azurea parva); Herbarium (O. azurea parva); Herbarium (O. azurea parva); Herbarium (O. azurea parva); Painting (possible O. azurea)

See O. chisosensis

See O. macrocentra

What is Opuntia azurea?

Opuntia azurea is an attractive prickly pear cactus from the Big Bend Region of Texas that is related to O. macrocentra. 

Details

A full technical description of this Opuntia and its proposed varieties begins on page 130 of The Cacti of the Trans-Pecos and Adjacent Areas (Powell and Weedin, 2004). 

Powell and Weedin described five varieties of O. azurea.

  • aureispina
  • azurea
  • discolor
  • diplopurpurea
  • parva

We include a sixth possible variety of this prickly pear that is undescribed. We provisionally refer to it as O. azurea casteretti. Perhaps O. azurea casteretii it is only a white-spined version of O. azurea diplopurpurea. Powell and Weedin considered these white-spined plants to be variants of O. macrocentra and nothing more.

O. azurea is tetraploid or hexaploid depending upon the report. Perhaps polidy varies with variety, but there is no evidence to support this idea. 

Other Notes

This Opuntia is a wide-ranging (into Mexico) and variable species. Depending upon the variety, the plant may be purple at the cladode base or may turn entirely purple in winter. Spines may be slender or robust. Also varieties are differentiated by height with some 1 m or taller and others less than 1 m. Additionally, cladode size may differentiate varieties. 

The Flora of North America does not recognize this taxon. 

O. azurea is cold-hardy and attractive in any collection. 

 

 

Opuntia aurea

Opuntia aurea, Zion
Opuntia aurea, Zion

Baxter, Cactus and Succulent Journal (U.S.) 5(6): 489, 1933

Holotype; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium

Original Description

What is Opuntia aurea?

Opuntia aurea is a prickly pear cactus that grows in southern UT and northern AZ. It is prostrate and forms irregularly sprawling plants to about 1 m across. A single pad may grow upright now and then.

Details

The cladodes are often oval but may also be broadly obovate up to 10(15) cm long. Cladodes have a thick look and they may become pink or purple in winter. Areoles on this Opuntia may be slightly sunken. O. aurea may be spineless or may have a few spines to multiple spines. Spines may be in the distal areoles only or on the faces of the cladode too. Excessively spiny plants may represent introgression from adjacent species. 

Flowers are pale-yellow, yellow, apricot-pink, and even strongly pink. Seeds are often circular and up to 7-8 mm in diameter or a bit more; arils may be 1-2 mm. Fruits of this prickly pear typically have no spines, but there may sometimes be one or more at the apex. Fruit is dry at maturity.

O. aurea is hexaploid.

Other notes. 

Because many plants are without spines, and because the areoles may be sunken, the plant was considered to be closely related to O. basilaris at one time. But, the two are rather different. Perhaps O. aurea has an O. basilaris-type plant in its background. 

O. aurea is a beautiful garden plant and does not become too large if modestly trimmed. Some forms are nicely cold-hardy. Flowers my be yellow, apricot, pink, and magenta. Some forms turn strongly red-purple in the winter. 

Special thanks to the Cactus and Succulent Society Journal for permission to reproduce the original description.