Pereskia is a genus of 17 tropical species and varieties of cacti that do not look much like other types of cacti, having substantial leaves and thin stems. They originate from the region between Brazil and Mexico. . Members of this genus are usually referred to as lemon vines, rose cacti or leaf cacti, though the latter also refers to the genus Epiphyllum. The genus is named after Nicolas-Claude Fabri de Peiresc, a 16th century French botanist, which also has been given its own subfamily Pereskioideae, which consists of this one genus.

Species of Pereskia generally resemble other types of plants, such as roses. Pereskia species have large, bright green, privet-like leaves and long spiny stems. Not always succulent plants, they can be classified as shrubs, climbing plants or slightly succulent trees. However, close examination shows spines developing from areoles, and the distinctive floral cup of the cactus family. Unlike Pereskiopsis, Maihuenia, Quiabentia and Austrocylindropuntia which have persistent succulent leaves, Pereskia is the only cactus genus that has persistent non-succulent leaves. It is believed that the ancestor of all cacti resembled Pereskia.

Description

Plants leafy and spiny, treelike, shrubby, and often scrambling. Majority species may be treelike or shrubby, 2 - 7 m high, heighest at 10 m. Pereskia aculeata forms clambering shrubs or climbing vines 3 - 10 m long. Roots sometimes thickened and tuberous. Leaves alternate, broad, flattened, deciduous, usually with petioles, 2 – 20 cm long. Areoles in the axils of the leaves, usually with wool, bearing spines and leaves. Spines 0 – 8 on young primary areolas on twigs, to numerous on trunk (15 - 40, max. 120), unequal in length 2 – 12 cm, straigh, usually black. Flowers solitary or in a inflorescences of 2 - 15 flowers (P. aceulata 70, P. grandiflora 10 – 30), 2 - 8 cm in diameter, usually pink, rose, purple, sometimes orange, yellow, white, cream. Fruits solitary or clustered, variable in shape, oblonge, pear shaped, usually green or yellowgreen in maturity, also orange, reddish, brownish, 2 - 7, max. 10 cm long. Three species have fruits very small, 0,5 – 1,5 cm globbose, glossy black. Seeds 2 – 7 mm large, obovate to kidney shaped, glossy black.

Distribution

Most of the species are found in dry forests or thorny scrub, in tropical climates with a dry season of two to five months. The two clades of Pereskia differ in their geographical distribution: with one exception.

Clade A

Clade A is found on Pacific coastal area, around the Gulf of Mexico and the Caribbean Sea .

Pereskia lychnidiflora Pacific coastal area from southern Mexico to Costa Rica in lowland dry forest from sea level to 1000 m (3300 ft).

Pereskia bleo Panama and Colombia along rivers and in secondary forests, from sea level to 500 m (1600 ft).

Pereskia guamacho Drier regions of Colombia and Venezuela, from sea level to 800 m (2600 ft); possibly also the Dutch Antilles.

Caribbean islands species. These plants are functionally dioecious, flowers imperfectly unisexual.

Pereskia marcanoi Semideciduous forests on Hispaniola at elevations of about 500 m (1600 ft).

Pereskia portulacifolia Hispaniola.

Pereskia quisqueyana Hispaniola. Endemic species. Only type locality in the southeastern part of the Dominican Republic at sea level .

Pereskia zinniiflora Lowlands of southern and southwestern Cuba.

Pereskia aureiflora One exception, occurs in clade B species area. Caatinga formation, Brazil, northeastern Minas Gerais and southern Bahia, at elevations of 300-700 m (980-2300 ft).

Clade B

Clade B occurs south of the Amazon Basin, in eastern part of Brazil, south to northern Uruguay and Argentina, Gran Chaco region, and lowlands and dry walleys on the Andes in Peru and Bolivia, though not on the Pacific side.

Brazil lowlands, caatinga formation:

Pereskia bahiensis Caatinga vegetation in Bahia, Brazil, at elevations of 400-900 m (1300-2950 ft).

Pereskia stenantha Caatinga vegetation of southern central Bahia, Brazil, at elevations of 400-600 m (1300-2000 ft).

Pereskia grandifolia Eastern Brazil but has escaped cultivation in many places. Subspecies violacea Transition zone between forest and savanna at elevations of 600-1400 m (2000-4600 ft).

Pereskia nemorosa Drier forests and woodlands in lowlands in southern Brazil, Paraguay, northeastern Argentina, and northwestern Uruguay region.

Pereskia sacharosa The Gran Chaco including Mato Grosso region (Brazil, Bolivia, Paraguay), and lowlands of the Andes in northwestern Argentina at elevations of 1000-2500 m.(3300-8200 ft).

Pereskia diaz-romeroana Dry mountain valleys of central Bolivia at elevations of 1300-2000 m (4300-6600 ft).

Pereskia weberiana Dry forests in the Bolivian Andean valleys of the Rio Beni, at elevations of 1100-1900 m (3600-6200 ft)

Pereskia horrida Dry forest and brushland in the Peruan mountain valleys of the Maranon at elevations of 500-2100 (1600-6900 ft).

Pereskia aculeata Northern, eastern, and southeastern South America, and Caribbean. From sea level to 1000 m (3300 ft). Introduced in United States, Mexico, South Africa and Australia.

Phylogeny and evolution

A 2005 study suggested that the genus Pereskia was basal within the Cactaceae, but confirmed earlier suggestions that it was not monophyletic, i.e. did not include all the descendants of a common ancestor. The Bayesian consensus cladogram from this study is shown below.^[1]

The species studied divide into the two clades as shown below.

A more recent 2011 study using fewer genes also found that Pereskia was divided into these two clades.^[2]

The two clades of Pereskia differ in their geographical distribution: with one exception, Clade A is found around the Gulf of Mexico and the Caribbean Sea whereas Clade B occurs south of the Amazon Basin. Species of Pereskia within Clade A always lack two key features of the stem present in most of the remaining "caulocacti": like most non-cacti, their stems begin to form bark early in the plant's life and also lack stomata – structures which control the admission of air into a plant and hence control photosynthesis. By contrast, species of Pereskia Clade B typically delay forming bark and have stomata on their stems, thus giving the stem the potential to become a major organ for photosynthesis.^[1]

If Pereskia is divided into two genera, based on these two clades, then Rhodocactus is a possible name for Clade A.^[3]

Taxonomy

Detail of the flower of Pereskia grandifolia

Stem of a tree-shaped Pereskia grandifolia

Most likely Charles Plumier collected the first Pereskia specimens from the Caribbean between 1689 and 1695, but none of these have survived. Although Plumier described Pereskia in 1703, Linnaeus placed Plumier's two species in his Cactus, as 'C. pereskia and C. portacifolius. Philip Miller brought the original name back in 1754, and so by the rules of botanical nomenclature, he is credited as the author.

The genus Rhodocactus (A.Berger) F.M.Knuth has been brought into synonymy with this genus, as well as different orthographic variants: Peirescia Zucc. (orth. var.), Peireskia Steud. (orth. var.) and Perescia Lem. (orth. var.).

Species recognized by International Cactaceae Systematics Group. (Anderson E. F., 2001)

Clade A

01. Pereskia aureiflora Ritter, 1979

02. Pereskia bleo (Kunth) De Candolle, 1828

03. Pereskia guamacho F.A.C.Weber, 1898

04. Pereskia lychnidiflora De Candolle, 1828

05. Pereskia marcanoi Areces Mallea, 1992

06. Pereskia portulacifolia (Linnaeus) De Candolle, 1828

07. Pereskia quisqueyana Liog, 1980

08. Pereskia zinniiflora De Candolle, 1828

Clade B

09. Pereskia aculeata P.Miller, 1768

+ Pereskia aculeata "Godseffiana" (hort.) - cultivar

+ Pereskia aculeata var. rubescens

10. Pereskia bahiensis Gürke, 1908

11. Pereskia diaz-romeroana Cárdenas, 1950

12. Pereskia grandifolia Haworth, 1821

+ Pereskia grandifolia subsp. violacea (Leuenberger) N. P. Taylor &Zappi 1997

13. Pereskia horrida De Candolle, 1828

+ Pereskia horrida subsp. rauhii (Backeberg) Ostolaza 1998.

14. Pereskia nemorosa Rojas, 1897

15. Pereskia sacharosa Grisebach, 1879

16. Pereskia stenantha Ritter, 1979

17. Pereskia weberiana K.Schumann, 1898

Synonyma

Pereskia colombiana = Pereskia guamacho

Pereskia corrugata = Pereskia bleo

Pereskia cubensis = Pereskia zinniiflora

Pereskia godseffiana = Pereskia aculeata

Pereskia humboldtii = Pereskia horrida

Pereskia philippi = Maihuenia poeppigii

Pereskia subulata = Austrocylindropuntia subulata

Pereskia vargasii = Pereskia horrida

Pereskia zehntneri = Quiabentia zehntneri

Pereskia zinniaefolia = Pereskia ziniiflora

Uses

The genus is not of great economic importance.

Pereskia aculeata The fruit are edible, widely cultivated. Fruits containing numerous small seeds. It somewhat resembles the gooseberry in appearance and is of excellent flavor. This plant is a declared weed in South Africa.

Pereskia guamacho The fruit are edible, coltected from wild plants.

Pereskia bleo The crushed leaves have been used to clarify drinking water.

Pereskia lychnidiflora The spines are 12 cm long and have been used as needles in Guatemala.

Pereskia grandifolia Cultivated for flowers.

The most common usage being as hedges; they are easily transplanted and quickly grow into an impenetrable thicket, as well as flowering prolifically.

Pereskia aculeata In horticulture being more tolerant of moisture than more succulent cacti, they can be used as rootstock for grafting of Zygocactus to create miniature trees.

References

1. ^ ^{a b} Edwards, Erika J.; Nyffeler, Reto & Donoghue, Michael J. (2005), "Basal cactus phylogeny: implications of Pereskia (Cactaceae) paraphyly for the transition to the cactus life form", American Journal of Botany 92 (7): 1177–1188, doi:10.3732/ajb.92.7.1177
2. ^ Bárcenas, Rolando T.; Yesson, Chris & Hawkins, Julie A. (2011), "Molecular systematics of the Cactaceae", Cladistics 27 (5): 470–489, doi:10.1111/j.1096-0031.2011.00350.x
3. ^ Stevens, P.F. (2001 onwards), "Cactaceae", Angiosperm Phylogeny Website, http://www.mobot.org/mobot/research/apweb/orders/caryophyllalesweb.htm#Cactaceae, retrieved 2012-02-20

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Literature

• Anderson, Edward F. (2001). The Cactus Family. Timber Press. pp. 566–572.
• Leuenberger, Beat (1986). "Pereskia (Cactaceae)". Memoirs of the New York Botanical Garden 14.
• Charles A. Butterworth and Robert S. Wallace, "Molecular Phylogenetics of the Leafy Cactus Genus Pereskia (Cactaceae)", Systematic Botany 30(4):800-808. 2005.
• Beat Ernst Leuenberger, "Pereskia, Maihuenia, and Blossfeldia —Taxonomic History, Updates, and Notes", Haseltonia 14 : 54-93. 2008