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Succulent plants store water in their fleshy stems, or leaves, such as this Aloe

In botany, succulent plants, also known as succulents, are plants that have some parts that are more than normally thickened and fleshy, usually to retain water in arid climates or soil conditions. The word "succulent" comes from the Latin word sucus, meaning juice, or sap.^[1] Succulent plants may store water in various structures, such as leaves and stems. Some definitions also include roots, thus geophytes that survive unfavorable periods by dying back to underground storage organs may be regarded as succulents. In horticultural use, the term "succulent" is sometimes used in a way which excludes plants that botanists would regard as succulents, such as cacti. Succulents are often grown as ornamental plants because of their striking and unusual appearance.

Many plant families have multiple succulents found within them (over 25 plant families).^[2] In some families, such as Aizoaceae, Cactaceae, and Crassulaceae, most species are succulents. The habitats of these water preserving plants are often in areas with high temperatures and low rainfall. Succulents have the ability to thrive on limited water sources, such as mist and dew, which makes them equipped to survive in an ecosystem which contains scarce water sources.

Definition

Center of a succulent (Aloe polyphylla)

A general definition of succulents is that they are drought resistant plants in which the leaves, stem or roots have become more than usually fleshy by the development of water-storing tissue.^[3] Other sources exclude roots as in the definition "a plant with thick, fleshy and swollen stems and/or leaves, adapted to dry environments."^[4] This difference affects the relationship between succulents and "geophytes" – plants that survive unfavorable seasons as a resting bud on an underground organ.^[5] These underground organs, such as bulbs, corms and tubers, are often fleshy with water-storing tissues. Thus if roots are included in the definition, many geophytes would be classed as succulents. Plants adapted to living in dry environments such as succulents are termed xerophytes. However, not all xerophytes are succulents, since there are other ways of adapting to a shortage of water, e.g., by developing small leaves which may roll up or having leathery rather than succulent leaves.^[6] Nor are all succulents xerophytes, since plants like Crassula helmsii are both succulent and aquatic.^[7]

Those who grow succulents as a hobby use the term in a different way to botanists. In horticultural use, the term succulent regularly excludes cacti. For example, Jacobsen's three volume Handbook of Succulent Plants does not cover cacti,^[8] and "cacti and succulents" is the title or part of the title of many books covering the cultivation of these plants.^[9][10][11] However, in botanical terminology, cacti are succulents.^[3] Horticulturists may also exclude other groups of plants, e.g., bromeliads.^[12] A practical, but unscientific, horticultural definition is "a succulent plant is any desert plant that a succulent plant collector wishes to grow."^[13] Such plants less often include geophytes (in which the swollen storage organ is wholly underground) but do include plants with a caudex,^[14] which is a swollen above-ground organ at soil level, formed from a stem, a root or both.^[5]

A further difficulty is that plants are not either succulent or non-succulent. In many genera and families there is a continuous gradation from plants with thin leaves and normal stems to those with very clearly thickened and fleshy leaves or stems, so that deciding what is a succulent is often arbitrary. Different sources may classify the same species differently.^[15]

Appearance

A collection of succulent plants, including cacti, from the Jardin botanique d'Èze, France

The storage of water often gives succulent plants a more swollen or fleshy appearance than other plants, a characteristic known as succulence. In addition to succulence, succulent plants variously have other water-saving features. These may include:

• 
  Crassulacean acid metabolism (CAM) to minimize water loss


• absent, reduced, or cylindrical-to-spherical leaves


• reduction in the number of stomata
  


• stems as the main site of photosynthesis, rather than leaves


• compact, reduced, cushion-like, columnar, or spherical growth form


• ribs enabling rapid increases in plant volume and decreasing surface area exposed to the sun


• waxy, hairy, or spiny outer surface to create a humid micro-habitat around the plant, which reduces air movement near the surface of the plant, and thereby reduces water loss and creates shade


• roots very near the surface of the soil, so they are able to take up moisture from very small showers or even from heavy dew
  


• ability to remain plump and full of water even with high internal temperatures (e.g., 52 °C or 126 °F)^[16]
  


• very impervious outer cuticle (skin)^[16]
  


• 
  mucilaginous substances, which retain water abundantly^[16]
  

Habitat

Many succulents come from dry areas such as steppes, semi-desert, and desert. High temperatures and low precipitation force plants to collect and store water to survive long dry periods. Some species of cactus can survive for months without rainfall.^[17] Succulents may occasionally occur as epiphytes, growing on other plants with limited or no contact with the ground, and are dependent on their ability to store water and gain nutrients by other means; this niche is seen in Tillandsia. Succulents also occur as inhabitants of sea coasts and dry lakes, which are exposed to high levels of dissolved minerals that are deadly to many other plant species.

Families and genera

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Apocynaceae: Pachypodium lealii, stem succulent

Asphodelaceae: Haworthia arachnoidea, leaf succulent

Asphodelaceae: Astroloba tenax, leaf succulent

Cactaceae: Rebutia muscula, stem succulent

Crassulaceae: Crassula ovata, stem and leaf succulent

Euphorbiaceae: Euphorbia obesa ssp. symmetrica, stem succulent

Cylindropuntia imbricata: stem, woody succulent

Malvaceae: Adansonia digitata, stem succulent

Moringaceae: Moringa ovalifolia, stem succulent

Asparagaceae: Beaucarnea recurvata, stem succulent

Asparagaceae: Dracaena draco, stem succulent

Euphorbia resinifera

Succulents kept at 77 °F (25 °C) in a Connecticut greenhouse

Kalanchoe longiflora

Echeveria derenbergii

Plant orders, families, and genera in which succulent species occur are listed below.

Order Alismatales

• 
  Araceae: Zamioculcas
  

Order Apiales

• 
  Apiaceae^[18]: Azorella, Crithmum
  


• 
  Araliaceae: Cussonia
  

Order Asparagales

• 
  Amaryllidaceae (geophytes): Amaryllis, Boophane, Clivia, Crinum, Cryptostephanus, Cyrtanthus, Haemanthus, Rauhia, Scadoxus, Stenomesson
  


• 
  Asparagaceae
  
  
  
  • 'Agavoideae : Agave, Beschorneria, Dracaena, Furcraea, Hesperaloe, Hesperoyucca, Manfreda, Polianthes, Yucca
    
  
  
  • 
    Lomandroideae: Cordyline
    
  
  
  • 
    Nolinoideae: Beaucarnea, Calibanus, Dasylirion, Nolina, Sansevieria
    
  
  
  • 
    Scilloideae (Hyacinthaceae): Albuca, Bowiea, Daubenya, Drimia, Eucomis, Lachenalia, Ledebouria, Massonia, Ornithogalum, Scilla, Urginea, Veltheimia
    
  
  
  
  


• 
  Doryanthaceae: Doryanthes
  


• 
  Orchidaceae: Acampe, Aerangis, Ansellia, Bolusiella, Bulbophyllum, Cirrhopetalum, Calanthe, Cyrtorchis, Eulophia, Liparis, Oberonia, Oeceoclades, Polystachya, Tridactyle, Vanilla
  

• 
  Asphodelaceae
  
  
  
  • subfamily Asphodeloideae: Aloe (succulents and succulent geophytes), Astroloba, Tulista, × Astrolista, Bulbine (succulent geophytes, succulents, and geophytes), Bulbinella (geophyte), Chortolirion (succulent geophytes), Gasteria, Haworthia, Trachyandra (succulent geophytes and succulents),
  
  
  • subfamily Xanothorrhoeoidae: Xanthorrhoea
    
  
  
  
  

Order Asterales

• 
  Asteraceae: Arctotheca, Baeriopsis, Chrysanthemoides, Coulterella, Crassocephalum, Didelta, Emilia, Eremothamnus, Gymnodiscus, Gynura, Hillardiella (geophyte), Lopholaena, Monoculus, Nidorella, Osteospermum, Othonna (succulents and succulent geophytes), Phaneroglossa, Poecilolepis, Polyachyrus, Pteronia, Senecio, Solanecio,Tripteris
  


• 
  Campanulaceae: Brighamia
  

Order Brassicales

• 
  Brassicaceae: Heliophila, Lepidium
  


• 
  Capparidaceae: Maerua
  


• 
  Caricaceae: Carica, Jacarathia
  


• 
  Moringaceae: Moringa
  

Order Caryophyllales

• 
  Aizoaceae: Corbichonia, Gisekia, Herreanthus, Limeum, Ophthalmophyllum, Saphesia
  
  
  
  • subfamily Aizooideae: Acrosanthes, Aizoanthemum, Aizoon, Galenia, Gunniopsis, Plinthus, Tetragonia
    
  
  
  • subfamily Mesembryanthemoideae (syn. Mesembryanthemaceae^[19]): Aptenia, Aridaria, Aspazoma, Brownanthus, Calamophyllum, Caulipsilon, Conophytum, Dactylopsis, Erepsia, Hameria, Hartmanthus, Hymenogyne, Marlothistela, Mesembryanthemum, Phiambolia, Phyllobolus, Prenia, Psilocaulon, Ruschiella, Sarozona, Sceletium, Synaptophyllum
    
  
  
  • subfamily Ruschioideae:
    
    
    
    • tribe Apatesieae: Apatesia, Carpanthea, Caryotophora, Conicosia, Hymenogyne, Saphesia, Skiatophytum
      
    
    
    • tribe Dorotheantheae: Aethephyllum Cleretum Dorotheanthus
      
    
    
    • tribe Ruschiae: Acrodon, Aloinopsis, Amphibolia, Antegibbaeum, Antimima, Arenifera, Argyroderma, Astridia, Bergeranthus, Bijlia, Braunsia, Brianhuntleya, Carpobrotus, Carruanthus, Cephalophyllum, Cerochlamys, Chasmatophyllum, Cheiridopsis, Circandra, Conophytum, Corpuscularia, Cylindrophyllum, Delosperma, Dicrocaulon, Didymaotus, Dinteranthus, Diplosoma, Disphyma, Dracophilus, Drosanthemum, Eberlanzia, Ebracteola, Enarganthe, Erepsia, Esterhuysenia, Faucaria, Fenestraria, Frithia, Gibbaeum, Glottiphyllum, Hallianthus, Hereroa, Ihlenfeldtia, Imitaria, Jacobsenia, Jensenobotrya, Jordaaniella, Juttadinteria, Khadia, Lampranthus, Lapidaria (plant), Leipoldtia, Lithops, Machairophyllum, Malephora, Mestoklema, Meyerophytum, Mitrophyllum, Monilaria, Mossia, Muiria, Namaquanthus, Namibia, Nananthus, Nelia, Neohenricia, Octopoma, Odontophorus, Oophytum, Ophthalmophyllum, Orthopterum, Oscularia, Ottosonderia, Pleiospilos, Polymita, Psammophora, Rabiea, Rhinephyllum, Rhombophyllum, Ruschia, Ruschianthemum, Ruschianthus, Schlechteranthus, Schwantesia, Scopelogena, Smicrostigma, Stayneria, Stoeberia, Stomatium Tanquana Titanopsis, Trichodiadema, Vanheerdea, Vanzijlia, Vlokia, Wooleya, Zeuktophyllum
      
    
    
    
    
  
  
  • subfamily Sesuvioideae: Cypselea, Sesuvium, Trianthema, Tribulocarpus, Zaleya
    
  
  
  
  


• 
  Amaranthaceae:
  
  
  
  • subfamily Amaranthoideae: Arthraerva
    
  
  
  • subfamily Chenopodioideae (family Chenopodiaceae):^[20]) Atriplex, Chenopodium, Dissocarpus, Einadia, Enchylaena, Eremophea, Halopeplis, Maireana, Malacocera, Neobassia, Osteocarpum, Rhagodia, Roycea, Halosarcia, Salicornia, Salsola, Sarcocornia, Sclerochlamys, Sclerolaena, Suaeda, Tecticornia, Threlkeldia
    
  
  
  
  


• 
  Basellaceae: Anredera, Basella
  


• 
  Cactaceae: Acanthocalycium, Acanthocereus, Ariocarpus, Armatocereus, Arrojadoa, Arthrocereus, Astrophytum, Austrocactus, Aztekium, Bergerocactus, Blossfeldia, Brachycereus, Browningia, Brasilicereus, Calymmanthium, Carnegiea, Cephalocereus, Cephalocleistocactus, Cereus, Cintia, Cipocereus, Cleistocactus, Coleocephalocereus, Copiapoa, Corryocactus, Coryphantha, Dendrocereus, Denmoza, Discocactus, Disocactus, Echinocactus, Echinocereus, Echinopsis, Epiphyllum, Epithelantha, Eriosyce, Escobaria, Escontria, Espostoa, Espostoopsis, Eulychnia, Facheiroa, Ferocactus, Frailea, Geohintonia, Gymnocalycium, Haageocereus, Harrisia, Hatiora, Hylocereus, Jasminocereus, Lasiocereus, Leocereus, Lepismium, Leptocereus, Leuchtenbergia, Lophophora, Maihuenia, Malacocarpus, Mammillaria, Mammilloydia, Matucana, Melocactus, Micranthocereus, Mila, Monvillea, Myrtillocactus, Neobuxbaumia, Neolloydia, Neoraimondia, Neowerdermannia, Obregonia, Opuntia, Oreocereus, Oroya, Ortegocactus, Pachycereus, Parodia, Pediocactus, Pelecyphora, Peniocereus, Pereskia, Pereskiopsis, Pilosocereus, Polaskia, Praecereus, Pseudoacanthocereus, Pseudorhipsalis, Pterocactus, Pygmaeocereus, Quiabentia, Rauhocereus, Rebutia, Rhipsalis, Samaipaticereus, Schlumbergera, Sclerocactus, Selenicereus, Stenocactus, Stenocereus, Stephanocereus, Stetsonia, Strombocactus, Tacinga, Thelocactus,Trichocereus Turbinicarpus, Uebelmannia, Weberbauerocereus, Weberocereus, Yungasocereus
  


• 
  Didiereaceae: Alluaudia, Alluaudiopsis, Decaria, Didierea
  


• 
  Molluginaceae: Hypertelis
  


• 
  Phytolaccaceae: Phytolacca
  


• 
  Portulacaceae: Amphipetalum, Anacampseros, Avonia, Calyptrotheca, Ceraria, Cistanthe, Calandrinia, Dendroportulaca, Grahamia, Lewisia, Parakeelya,^[21]Portulaca, Portulacaria, Schreiteria, Talinella, Talinum
  

Order Commelinales

• 
  Commelinaceae: Aneilema, Callisia, Cyanotis, Tradescantia, Tripogandra
  

Order Cornales

• 
  Loasaceae: Schismocarpus
  

Order Cucurbitales

• 
  Begoniaceae: Begonia
  


• 
  Cucurbitaceae: Acanthosicyos, Apodanthera, Brandegea, Cephalopentandra, Ceratosanthes, Citrullus, Coccinia, Corallocarpus, Cucumella, Cucumis, Cucurbita, Cyclantheropsis, Dactyliandra, Dendrosicyos, Doyera, Eureindra, Fevillea, Gerrandanthus, Gynostemma, Halosicyos, Ibervilla, Kedostris, Lagenaria, Marah, Momordica, Neoalsomitra, Odosicyos, Parasicyos, Syrigia, Telfairia, Trochomeria, Trochomeriopsis, Tumamoca, Xerosicyos, Zehneria, Zygosicyos
  

Order Dioscoreales

• 
  Dioscoreaceae: Dioscorea
  

Order Ericales

• 
  Balsaminaceae: Impatiens
  


• 
  Ericaceae: Sphyrospermum
  


• 
  Fouquieriaceae: Fouquieria
  

Order Fabales

• 
  Fabaceae: Delonix, Dolichos, Erythrina, Lotononis, Neorautanenia, Pachyrhizus, Tylosema
  

Order Gentianales

• 
  Apocynaceae: Adenium, Mandevilla, Pachypodium, Plumeria
  
  
  
  • subfamily Asclepiadoideae (syn. Asclepiadaceae): Absolmsia, Australluma, Aspidoglossum, Aspidonepsis, Baynesia, Brachystelma, Ceropegia, Chlorocyathus, Cibirhiza, Cordylogyne, Cynanchum, Dischidia, Dischidiopsis, Duvaliandra, Eustegia, Fanninia, Fockea, Glossostelma, Hoya, Ischnolepis, Lavrania, Marsdenia, Miraglossum, Odontostelma, Ophionella, Orbeanthus, Pachycarpus, Parapodium, Periglossum, Petopentia, Raphionacme, Riocreuxia, Sarcorrhiza, Schizoglossum, Schlechterella, Stathmostelma, Stenostelma, Stomatostemma, Trachycalymma, Trichocaulon, Tylophora, Woodia, Xysmalobium
    
    
    
    • tribe Asclepiadeae:
      
      
      
      • subtribe Asclepiadne: Asclepias,
      
      
      • subtribe Cynanchinae: Sarcostemma,
      
      
      • subtribe Gonolobinae: Matelea,
      
      
      
      
    
    
    • tribe Maxillarieae:
      
      • subtribe Lycastinae: Rudolfiella
        
      
      
    
    
    • tribe Stapeliae: Angolluma, Caralluma, Desmidorchis, Duvalia, Echidnopsis, Edithcolea, Frerea, Hoodia, Huernia, Huerniopsis, Larryleachia, Notechidnopsis, Orbea (plant), Orbeopsis, Piaranthus, Pachycymbium, Pectinaria, Pseudolithos, Pseudopectinaria, Quaqua, Rhytidocaulon, Stapelia, Stapelianthus, Stapeliopsis, Tavaresia, Tridentea, Tromotriche, Whitesloanea
      
    
    
    
    
  
  
  • subfamily Periplocoideae:
    
    • tribe Cryptolepideae: Cryptolepis
      
    
    
  
  
  
  


• 
  Rubiaceae: Anthorrhiza, Anthospermum, Hydnophytum, Hydrophylax, Myrmecodia, Myrmephytum, Phylohydrax, Squamellaria
  

Order Geraniales

• 
  Geraniaceae: Monsonia, Pelargonium (succulents and geophytes), Sarcocaulon
  

Order Lamiales

• 
  Gesneriaceae: Aeschynanthus, Alsobia, Chirita, Codonanthe, Columnea, Nematanthus, Sinningia, Streptocarpus
  


• 
  Lamiaceae: Aeollanthus, Dauphinea, Perrierastrum, Plectranthus, Rotheca, Solenostemon, Tetradenia, Thorncroftia
  


• Lentibulariaceae


• 
  Pedaliaceae: Holubia, Pterodiscus, Sesamothamnus, Uncarina
  

Order Malpighiales

• 
  Euphorbiaceae: Cnidoscolus, Euphorbia, Jatropha, Monadenium, Pedilanthus, Phyllanthus, Synadenium
  


• 
  Passifloraceae: Adenia
  


• 
  Phyllanthaceae: Phyllanthus
  

Order Malvales

• Cochlospermaceae


• 
  Malvaceae: Adansonia, Cavanillesia, Ceiba, Pseudobombax
  
  • subgroup Sterculiaceae: Brachychiton, Sterculia
    
  
  

Order Myrtales

• 
  Melastomataceae: Medinilla
  

Order Oxalidales

• 
  Oxalidaceae (geophytes): Oxalis
  

Order Piperales

• 
  Piperaceae: Peperomia
  

Order Poales

• 
  Bromeliaceae: Abromeitiella, Aechmea, Ananas, Catopsis, Connellia, Dyckia, Hechtia, Neoregelia, Puya, Tillandsia, Vriesea
  


• 
  Poaceae: Dregeochloa^[22]
  

Order Ranunculales

• 
  Menispermaceae: Chasmanthera, Stephania, Tinospora
  

Order Rosales

• 
  Moraceae: Dorstenia, Ficus
  


• 
  Urticaceae: Laportea, Obetia, Pilea, Pouzolzia, Sarcopilea
  

Order Santalales

• 
  Loranthaceae: Actinanthella, Agelanthus, Erianthemum, Helixanthera, Moquiniella, Oncocalyx, Pedistylis, Plicosepalus, Septulina, Tapinanthus, Vanwykia
  


• 
  Viscaceae(syn. Santalaceae): Viscum
  

Order Sapindales

• 
  Anacardiaceae: Operculicaria, Pachycormus
  


• 
  Burseraceae: Boswellia, Bursera, Commiphora
  


• 
  Meliaceae: Entandrophragma
  


• 
  Sapindaceae: Erythrophysa
  

Order Saxifragales

• 
  Crassulaceae: Adromischus, Aeonium, Aichryson, Cotyledon, Crassula, Cremnophila, Dudleya, Echeveria, Graptopetalum, Greenovia, Hylotelephium, Kalanchoe, Kungia, Lenophyllum, Meterostachys, Monanthes, Mucizonia, Orostachys, Pachyphytum, Perrierosedum, Petrosedum, Phedimus, Pistorinia, Prometheum, Pseudosedum, Rhodiola, Rosularia, Sedella, Sedum, Sempervivum, Sinocrassula, Thompsonella, Tylecodon, Umbilicus, Villadia^[23]
  


• Saxifragaceae

Order Solanales

• 
  Convolvulaceae: Ipomoea, Merremia, Stictocardia, Turbina (plant)
  


• 
  Solanaceae: Nolana
  

Order Vitales

• 
  Vitaceae: Cissus, Cyphostemma
  

Order Zygophyllales

• 
  Zygophyllaceae: Augea, Seetzenia, Zygophyllum
  

(unplaced order)* Boraginaceae: Heliotropium
(unplaced order)* Icacinaceae: Pyrenacantha (geophyte)

For some families and subfamilies, most members are succulent; for example the Cactaceae, Agavoideae, Aizoaceae, and Crassulaceae.

The table below shows the number of succulent species found in some families:

Edgerton Park Conservancy succulent at dusk.

Cultivation

Succulent "wall" in a nursery in San Francisco, United States consisting of Sempervivum, Echeveria and Crassula.

Succulents are favored as houseplants for their attractiveness and ease of care. If properly potted, succulents require little maintenance to survive indoors.^[24] Succulents are very adaptable houseplants and will thrive in a range of indoor conditions.^[25] For most plant owners over-watering and associated infections are main cause of death in succulents.

Succulents can be propagated by different means. The most common is vegetative propagation; this includes cuttings where several inches of stem with leaves are cut and after healing produce a callus. After a week or so, roots may grow. A second method is division consisting of uprooting an overgrown clump and pulling the stems and roots apart. The easiest one is allowing the formation of callus from a leaf. The vegetative propagation can be different according to the species.^[26]

See also

• Cactus and Succulent Society of America


• Crassulacean acid metabolism

References

Bibliography

• 
  Anderson, Miles (1999), Cacti and Succulents : Illustrated Encyclopedia, Oxford: Sebastian Kelly, ISBN 978-1-84081-253-4
  


• 
  Beentje, Henk (2010), The Kew Plant Glossary, Richmond, Surrey: Royal Botanic Gardens, Kew, ISBN 978-1-84246-422-9
  


• 
  Compton, R.H., ed. (n.d.), Our South African Flora, Cape Times Ltd, OCLC 222867742 (publication date also given as 1930s or 1940s)


• 
  Hecht, Hans (1994), Cacti & Succulents (p/b ed.), New York: Sterling, ISBN 978-0-8069-0549-5
  


• 
  Hewitt, Terry (1993), The Complete Book of Cacti & Succulents, London: Covent Garden Books, ISBN 978-1-85605-402-7
  


• 
  Innes, Clive & Wall, Bill (1995), Cacti, Succulents and Bromeliads, London: Cassell for the Royal Horticultural Society, ISBN 978-0-304-32076-9
  


• 
  Jacobsen, Hermann (1960), A Handbook of Succulent Plants (Vols 1–3), Poole, Dorset: Blandford Press, ISBN 978-0-7137-0140-1
  


• 
  Martin, Margaret J. & Chapman, Peter R. (1977), Succulents and their cultivation, London: Faber & Faber, ISBN 978-0-571-10221-1
  


• 
  Rowley, Gordon D. (1980), Name that Succulent, Cheltenham, Glos.: Stanley Thornes, ISBN 978-0-85950-447-8
  

External links

Look up succulent in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Succulents.