Neotropical Cactaceae

Daniela Zappi

Royal Botanic Gardens, Kew, UK. 

Description

Trees, shrubs or herbs, sometimes epiphytes, with three distinct types of branch: normal vegetative branches, areoles (reduced branches that can originate stems, spines or flowering branches) and flowering branches. Developed leaves present in one subfamily (Pereskioideae), reduced leaves present in Opuntioideae, Cactoideae devoid of leaves. Branches green, photosynthetic, succulent, ribs and tubercles present. Spines organized within areoles, together with hairs and bristles, specialized serrated spines and glochid present only in Opuntioideae. Flowers generally showy, epigynous, with receptacular inferior ovary, solitary or in inflorescences, externally with areoles, bracts and many perianth segments arranged spirally and showing a transition between sepaloid (external) and petaloid (internal) segments, flower tube generally developed, nectar chamber above the ovary and basal region of the tube, stamens numerous, filaments fleshy; ovary unilocular, originated from the fusion of many carpels (generally number of carpels reflected in the number of stigma lobes). Fruits berry-like, fleshy, multi-seeded, indehiscent or dehiscent, seeds cochleariform, with bone-like testa in Opuntioideae, testa dark and normally shiny in Pereskoideae and Cactoideae.

Notes on delimitation

  • DNA studies show that Portulacaceae possibly cannot be separated from Cactaceae because it lacks autoapomorphies; Cactaceae however presents areoles which are not present as such in Portulacaceae.

Distribution in the Neotropics

  • Neotropical distribution with the exception of one species, Rhipsalis baccifera (J.S.Mill.) Stearn, distributed in the Old World.

Distinguishing characters (always present)

  • Presence of three types of branches: vegetative expanded branches, reduced structure bearing branches called areoles (specific to the family), flowering branches.
  • Receptacular inferior ovary.
  • Spines (sometimes lacking or profoundly modified).

Other important characters

  • Succulence.
  • Spines.
  • Many perianth transitional segments (sepals and petals).

Key differences from similar families

Number of genera

  • 124 genera, over 1,300 species.

Useful tips for generic identification

First subdivide in Subfamilies:

  • Opuntioideae have bony seeds, serrated spines and glochids.
  • Pereskoideae have really well developed leaves and are not very succulent.
  • Cactoideae are stem succulents without leaves, with black shiny seeds.

Useful characters to define tribes/genera:

  • With or without conspicuous areoles.
  • Presence/absence of ribs.
  • Flowering structure (cephalium).
  • Fruits (aspect, dehiscence).
  • Seed characters.

Notable genera and distinguishing features

  • Cereus Mill.: Tree-like with naked large nocturnal flowers and fruits dehiscent by longitudinal slits, 30+ species mostly S. American.
  • Pilosocereus Byles & G.D.Rowley: Shrubby to tree-like with nocturnal, dull, smelly flowers and fruits subglobose dehiscent by irregular slits, 30+ speices mostly S. American.
  • Melocactus (L.) Link & Otto: Globose, with cephalium and small diurnal red, pink or magenta flowers, fruits white to deep red, 30+ species South American and Caribbean. 
  • Epiphyllum Haw.: Foliose, epiphytic with showy, large flowers, 15+ species mostly Caribbean.   
  • Rhipsalis Gaertn.: Epiphytic, string-like, with small white flowers without tube and fleshy fruits, 30+ species, mostly Brazilian Atlantic forest.   
  • Mammillaria Haw.: Small globose to cylindric, with tubercles and two different types of areoles, latex sometimes present, small flowers appearing in rings around the stem, 50+ species mostly Mexican. 
  • Echinopsis Zucc.: Variable habit from tree-like to globose, large flowers white to deep red, externally with areoles and hairs, 50+ species mostly Andean.  
  • Parodia Speg.: Globose to cylindric, flowers diurnal yellow to red or pink, short tube.
  • Opuntia Mill.: Shrubs to tree-like plants with reduced, scale-like leaves and flattened pads with glochids and serrate spines, flower with well defined green pericarpel, no tube, sensitive stamens, c. 200+ species mostly Caribbean and North American.
  • Pereskia Mill.: Trees or climbers with well developed leaves, flowers without developed tube, white, orange, pink or red, fruits indehiscent with large seeds, c. 18 species South American and Caribbean.

Status

  • Cultivated under glass in temperate regions, naturalised outdoors in the Paleotropics (in Australia some Opuntia became weeds), especially Opuntia ficus-indica Mill. (from Mexico but widely cultivated and introduced in Mediterranean regions, nowadays part of the culture in Europe); endemic species are endangered through habitat destruction and modification (agriculture, irrigation) and, to a lesser scale, by overcollection by amateurs.

General notes

The three main centres of diversity of this largely Neotropical family are the highly endemic drylands of Mexico, the Argentinian/Bolivian Andes and Eastern Brazil. A large proportion of the species are endemic to deserts and arid regions, but there are also epiphytes in the wettest forests of the Neotropics. The taxonomy of this family has been shaped by the important contribution of amateurs, who discovered and described a large number of species, many of them in cultivation nowadays.

Important literature

Hunt, D., Taylor, N., Charles, G. 2006. The New Cactus Lexicon. 2 vols.

How to cite

Zappi, D. (2009). Neotropical Cactaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Cactaceae.htm.

Click images to enlarge


Austrocylindropuntia subulata, flower © Maximilian Weigend, Freie Universität Berlin.



Austrocylindropuntia subulata, whole plant © Maximilian Weigend, Freie Universität Berlin.



Brasiliopuntia brasiliensis © Daniela Zappi/Nigel Taylor, RBG, Kew.



Calymmanthium substerile © A. McRobb, RBG, Kew.



Cleistocactus candelilla © John Wood, Darwin Initiative Project 161/11/010



Copiapoa sp. © Daniela Zappi/Nigel Taylor, RBG, Kew.



Corryocactus brevistylus, flower © Maximilian Weigend, Freie Universität Berlin.



Corryocactus brevistylus, fruiting stem © Maximilian Weigend, Freie Universität Berlin.



Corryocactus brevistylus, flower, lateral view © Maximilian Weigend, Freie Universität Berlin.



Cumulopuntia ignescens, cladode, flower and fruit © Maximilian Weigend, Freie Universität Berlin.



Cumulopuntia ignescens, whole plant © Maximilian Weigend, Freie Universität Berlin.



Cumulopuntia ignescens, flowers © Maximilian Weigend, Freie Universität Berlin.



Discocactus catingicola © Daniela Zappi/Nigel Taylor, RBG, Kew.



Echinocereus peruvianus, flower © Maximilian Weigend, Freie Universität Berlin.



Echinocereus peruvianus, stem © Maximilian Weigend, Freie Universität Berlin.



Espostoa sp., whole plant © Maximilian Weigend, Freie Universität Berlin.



Espostoa sp., flower © Maximilian Weigend, Freie Universität Berlin.



Gymnocalycium pflanzii © Daniela Zappi/Nigel Taylor, RBG, Kew.



Leptocereus quadricostatus © Daniela Zappi/Nigel Taylor, RBG, Kew.



Melocactus zehntneri © Daniela Zappi/Nigel Taylor, RBG, Kew.



Neoraimondia herzogiana © John Wood, Darwin Initiative Project 161/11/010.



Cut flower of Opuntia showing inferior receptacular ovary © D. Zappi, RBG, Kew.



Parodia sp. © Daniela Zappi/Nigel Taylor, RBG, Kew.



Pereski zinniiflora © John Wood, Darwin Initiative Project 161/11/010.



Rhipsalis baccifera © Peter Gasson, RBG, Kew.