Opuntia caesia

Opuntia caesia
Opuntia caesia

Griffiths, Proceedings of the Biological Society of Washington 29(3): 13–14, 1916

Isotype; Herbarium; Herbarium; Herbarium

What is Opuntia caesia?

Opuntia caesia is a prickly pear cactus that is larger than O. phaeacantha. It may reach 2 m across and be about 60-70 cm tall with erect branches that rise from spreading, sprawling branches.


Cladodes on this Opuntia are typically 10-12 cm wide by 9-12 cm long, though they are variable. The pads may narrow to a semi-stipitate base. New growth is glaucous and blue-green. There are 2-4 spines the first year that are often dark (except for pale downward sloping spines). Longest spines can be 7-8 cm long. Old spines may be more numerous and are pale. Griffiths remarked that this Opuntia has nearly as much glaucous blue bloom as O. robusta. The blue color fades to greenish or yellow-green under drought stress or with age. 

The style is white and the stigma is green; filaments are yellow with greenish bases. The ripe fruit is purplish-red but the pulp is lighter. 

The plants are abundant around Crozier, AZ. They may be low in Crozier, but are taller in Toquerville, UT. The opuntia shares similarity with O. camanchica and O. phaeacantha, but the blue color makes them distinctive. When O. phaeacantha and O. caesia are growing together the first usually has larger pads with more areoles but is typically lower, and it definitely has less woody growth. 

The original plants were described from northern Arizona. See the original citation

Opuntia tardospina

Opuntia tardospina
Opuntia tardospina

Griffiths, Annual Report of the Missouri Botanical Garden 22: 34, 1911

Herbarium; Herbarium; Herbarium; Herbarium; Photograph (top photo, Britton and Rose, 1919, v1); Photograph (Britton and Rose, 1919, v1); Painting

What is Opuntia tardospina?

Opuntia tardospina is a large prickly pear cactus first reported from the Lampasas, TX region. Griffiths reported that this Opuntia was an unusual cactus for several reasons, not the least of which were the prominent areoles.


Cladodes are green or bluish-green and up to 24 by 30 cm, subcircular to obovate. Though spines are mostly absent, some yellow ones do occur that recurve or slope downwards. Under garden conditions, spines may be frequent. The glochids are numerous and prominent, up to 12 to 15 mm-long, sometimes even on pads of the current year. Areoles are prominent, up to 1 cm across in old growth and raised by 2 to 4 mm. Finally, the prominent glochids can cover old stems as in the case of O. chlorotica santa-rita

Flowers are yellow and fruit is broadly obovate to pyriform, with areoles about 15 mm apart. 

O. tardospina differs from O. aciculata in several ways. The pads are bluer and thicker, and the trunks have glochids. The plants in these photos have curved leaves on the ovaries, which is a feature of O. cacanapa. See the original description.



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

What is Opuntia chlorotica gosseliniana?

O. chlorotica gosseliniana is one of three varieties: chlorotica, santa-rita, and gosseliniana within the O. chlorotica complex as described by Ferguson (1988)


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 cyclindrical. This variety has smaller and relatively more slender fruit than vars chlorotica and santa-rita.

See the original description. O. chlorotica gosseliniana is diploid. 

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 a very uncommon Opuntia in the United States.  

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

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. 


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. 

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.”

Read the original description. O. chlorotica santa-rita is diploid.

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 7?). 

Opuntia sp nova aff macrocentra

Opuntia sp nova aff macrocentra
Opuntia sp nova aff macrocentra


This unidentified Opuntia  was observed growing in southern New Mexico, near El Paso, TX, and in adjacent Mexico. This cactus grows with O. macrocentra and is similar to O. macrocentra, but it is more upright, has a different bloom period, and is a slightly taller prickly pear. These opuntias have a gray-blue color, and the spines are pale at their tips.

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

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


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 upper edge areoles. 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 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. See the original description. O. macrocentra may be tetraploid or diploid. O. macrocentra minor has been described, and it is diploid (see Powell and Weedin).

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 and warmer if the climate is not to wet. 

Opuntia confusa

Opuntia confusa
Opuntia confusa

Griffiths, Proceedings of the Biological Society of Washington 27(6): 28, 1914

Holotype; Isotype; Isotype; Isotype; Isotype; Isotype; Herbarium; Herbarium

See O. dulcis

What is Opuntia confusa?

Opuntia confusa is an interesting prickly pear because some cladodes have spination similar to that of O. engelmannii, whereas other cladodes have spination similar to that of O. dulcis


In some of the obovate to subcircular pads the spines are longer than on other pads. These longer spines are heavy, angular, and spreading as in O. engelmannii. Three or more major spines may be present. In contrast, spines on other pads are slender, one porrect and one deflexed (O. dulcis like). Thus, there are two different types of spination in O. confusa

The yellow flowers are 5-8 cm in diameter and all darken to red or near-red with age. Filaments are yellow and anthers are yellow. The style is pale and the stigma is green. Fruit is short-pyriform to subglobose and red. The fruit has a noticeable bloom that is lost at complete ripening when the fruit is dull red. Fruit spines may be reddish-brown. 

O. confusa resembles O. dulcis in overall aspect and grows along side it in some locations. However, the two generally do not produce hybrids. The two prickly pears are similar in growth form and habit. However, when they are growing together it can be seen that O. confusa is always smaller, rarely reaching 40 cm tall, and O. confusa pads average smaller as well. 

O. confusa typically has large areoles with more irregularly sized glochids that are scattered throughout areoles as in O. engelmannii. In contrast, O. dulcis generally has a tuft of glochids at the apex of an areole. O. confusa is a bluer plant than O. dulcis. Older (oldest) spines are darker on O. confusa than those of O. dulcis. The oldest spines of O. dulcis (on the oldest cladodes) may be black, especially in the western part of its range. See a table that compares  O. confusa with O. dulcis. Read the original description.


Opuntia cacanapa (incl O. ellisiana)

Opuntia cacanapa
Opuntia cacanapa

Griffiths & Hare, New Mexico Agricultural Experiment Station Bulletin (New Mexico College of Agriculture and Mechanic Arts) 60: 47, 1906

IsotypeNeotypeHolotype (O. cacanapa ‘Ellisiana’); Isotype (O. cacanapa ‘Ellisiana’); Herbarium (O. cacanapa ‘Ellisiana’)

O. alta is another arborescent Opuntia

What is Opuntia cacanapa?

Opuntia cacanapa is a large prickly pear cactus that occurs in Brewster County, TX and southeast to the Gulf Coast as well as in adjacent Mexico. It may also occur inland on the South Texas Plains where it is sympatric with other Opuntia species.


O. cacanapa can reach 2-2.5 m tall. The largest branches/trunk may be 16 cm in diameter. O. cacanapa forms a large, open, branching prickly pear with blue-green and glaucous cladodes. The cladodes are up to 20 cm in longest diameter and are suborbicular, oval, or obovate. The 4-5 cm long spines of this Opuntia are yellow and sometimes brown or reddish-brown at the base. Spines may curve out from the areoles. Some plants may lack spines in most areoles. The stigma of the yellow flowers is pale, yellowish-green, or pale green. The leaves are  strongly recurved, more so than in most Opuntia species. O. alta has recurved leaves, but they don’t curl back as strongly. 

O. cacanapa ‘Ellisiana’ is garden variant of O. cacanapa that has no spines and essentially no glochids. O. cacanapa ‘Ellisiana’ may seem different from the parent Opuntia. However, O. cacanapa and O. cacanapa ‘Ellisiana’ share key features that demonstrate their relatedness: 1) strongly recurved leaves on cladodes and flowers, 2) pale stigmas with white styles, 3) white filaments with yellow anthers, 4) general shape and size of the fruits, 5) obovate or subcircular cladodes, 6) identical bloom periods, and 7) shrubby or arborescent growth. 

Lack of spines is a feature of some Opuntia species and is not unknown. However, lack of glochids is a very unusual condition in any prickly pear.

See the original description. O. cacanapa is diploid.

O. cacanapa ‘Ellisiana’ is cold hardy to about zero F, and without spines or glochids, it is a wonderful garden plant. It is not fast growing and can be kept small by pruning. 

Read more below thumbnails.


Top of page.

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; HerbariumHolotype (O. basilaris brachyclada); Herbarium (O.  basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris longiareolata); Herbarium (O. basilaris longiareolataHerbarium (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

What is Opuntia basilaris?

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


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.

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. 

There are at least 5 described varieties of this Opuntia that we recognize:

  • 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. Read the original description. O. basilaris is diploid, but O. basilaris treleasii is triploid and may represent a separate taxon.

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

HolotypeIsotype; Isotype; Herbarium; Herbarium; Herbarium; Herbarium; HerbariumHerbarium (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. A full technical description of this Opuntia appears on page 130 of The Cacti of the Trans-Pecos and Adjacent Areas (Powell and Weedin, 2004). 


The cladodes are glaucous blue-green, and areoles are 1.2 to 1.6 cm apart. When mature, spines are black, unequal, and up to 2.5 cm long. Flowers are yellow with red centers, essentially identical to those of O. macrocentra. Stigmas are pale green. This Opuntia is a wide-ranging (into Mexico) and variable species. The Flora of North America does not recognize this taxon. 

Powell and Weedin described five varieties of O. azurea.

  • aureispina
  • azurea
  • discolor
  • diplopurpurea A.M. Powell & J.F. Weedin
  • parva A.M. Powell & J.F. Weedin

We include a sixth possible variety of this prickly pear that is undescribed. We provisionally refer to it as O. azurea casteretti. Perhaps it is only a white-spined version of another Opuntia variety, O. azurea diplopurpurea. Powell and Weedin considered these white-spined plants to be variants of O. macrocentra and nothing more. See the original description. O. azurea is tetraploid or hexaploid depending upon the report. Perhaps (not sure) polidy varies with variety. 

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.