succulent

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

Succulent plants, also known as succulents or fat plants, are water-retaining plants adapted to arid climates or soil conditions. Succulent plants store water in their leaves, stems, and also in roots. Geophytes that survive unfavourable periods by dying back to underground storage organs such as tuberous roots, corms, bulbs, and rhizomes, may be regarded as succulents.

Appearance

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 / 126 °F)^[1]
• very impervious outer cuticle (skin)^[2]
• mucilaginous substances, which retain water abundantly ^[3]

Habitat

Many succulents come from the dry areas of the tropics and subtropics, such as steppes, semi-desert, and desert. High temperatures and low precipitation force plants to collect and store water to survive long dry periods. Succulents also occur as epiphytes, "air plants", as such they have limited or no contact with the ground, and are dependent on their ability to store water. 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.

Evolution

The best-known succulents are cacti (family: Cactaceae). Virtually all cacti are succulents, but not all succulents are cacti. There is a significant difference between succulents that evolved in Africa and those that evolved in the Americas: the New World plants called cacti all have spines. No succulent plants arising in the Old World have spines although, through convergent evolution, there are similar species in the Old World that closely resemble species in the new world that do have spines. The functional nature of the shapes evolved independently in each hemisphere, even though the specific structures may differ. The spines of cacti arose from leaf structures.

To differentiate between these two basic types that seem so similar, but that are unrelated succulent plants, use of the terms, cactus or cacti, only should be used to describe succulents with spines. Popular collection of these types of plants has led to many Old World plants becoming established in the wild in the New World, and vice versa. One genus, Opuntia, is thought^{[by whom?]} to have floated from the New World to the Old on equatorial currents and colonized itself in Africa, being described very early in botanical descriptions. Salt tolerance may have facilitated this process if early explorers were not responsible for transporting the plants.

Families and genera

Apocynaceae: Pachypodium lealii, stem succulent

Asphodelaceae: Haworthia arachnoidea, 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

Nolinaceae: Beaucarnea recurvata, stem succulent

Ruscaceae: Dracaena draco, stem succulent

Euphorbia resinifera

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

• Agavaceae: Agave, Beschorneria, Chlorophytum, Furcraea, Hesperaloe, Hesperoyucca, Yucca
• Aizoaceae: Aizoanthemum, Aizoon, Galenia, Sesuvium, Tetragonia, Trianthema, Zaleya
  • subfamily Mesembryanthemoideae (syn. Mesembryanthemaceae^[4]): Acrodon, Aethephyllum, Aloinopsis, Amoebophyllum (non-current), Amphibolia, Antegibbaeum, Antimima, Apatesia, Aptenia, Arenifera, Argyroderma, Aridaria, Aspazoma, Astridia, Bergeranthus, Berrisfordia (non-current), Bijlia, Braunsia, Brianhuntlia, Brownanthus, Calamophyllum, Carpanthia, Carpobrotus, Carruanthus, Caryotophora, Caulipsilon, Cephalophyllum, Cerochlamys, Chasmatophyllum, Cheiridopsis, Circandra, Cleretum,Conicosia, Conophytum, Corpuscularia, Cylindrophyllum, Dactylopsis, Delosperma, Dicrocaulon, Dinteranthus, Diplosoma, Disphyma,Dorotheanthus, Dracophilus, Drosanthemum, Eberlanzia, Ebracteola, Ectotropis (non-current), Enarganthe, Erepsia, Esterhuysenia, Eurystigma (non-current), Faucaria, Fenestraria, Frithia, Gibbaeum, Glottiphyllum, Halenbergia (non-current), Hallianthus, Hameria, Hartmanthus, Hereroa, Herrea (non-current), Herreanthus (now Conophytum), Hydrodea (non-current), Hymenogyne, Ihlenfeldtia, Imitaria (non-current), Jacobsenia, Jensenbotrya, Jordaaniella, Juttadinteria, Kensitia (non-current), Khadia, Lampranthus, Lapidaria, Leipoldtia, Lithops, Machairophyllum, Malephora, Marlothistela, Maughaniella (non-current), Mesembryanthemum, Mestoklama, Meyerophytum, Micropterum (non-current), Mimetophytum (non-current), Mitrophyllum, Monilaria, Mossia, Muiria, Namaquanthus, Namibia, Nanathus, Nelia, Neohenricia, Neorhine (non-current), Nycteranthus (non-current), Octopoma, Odontophorus, Oophytum, Ophthalmophyllum (non-current), Orthopterum, Oscularia, Ottosonderia, Pherelobus (non-current), Phiambolia, Phyllobolus, Platythyra (non-current), Pleiospilos, Polymita, Prenia, Psammophora, Psicaulon, Rabiea, Rhinephyllum, Rhombophyllum, Ruschia, Ruschianthemum (non-current), Ruschianthus, Ruschiella, Saphesia, Sarozona,Sceletium, Schlecteranthus, Schwantesia, Scopologena, Semnanthe (now Erepsia), Skiatophytum, Smicrostigma, Sphalmanthus (non-current), Stayneria, Stoeberia, Stomatium, Synaptophyllum, Tanquana, Titanopsis, Trichodiadema, Vanheerea, Vanzijlia, Viokia, Wooleya, Zeuktophyllum
• Amaranthaceae: Arthraerua
• Amaryllidaceae (geophytes): Ammocharis, Apodolirion, Boophone, Brunsvigia, Crinum, Crossyne, Cryptostephanus, Cyrtanthus, Gethyllis, Habranthus, Haemanthus, Hessea, Nerine, Pancratium, Rauhia, Scadoxus, Strumaria, Zephyranthes,
• Anacardiaceae: Operculicaria, Pachycormus
• Apiaceae: Steganotaenia
• Apocynaceae: Adenium, Mandevilla, Pachypodium, Plumeria
  • subfamily Asclepiadoideae (syn. Asclepiadaceae): Absolmsia, Asclepias, Australluma, Aspidoglossum, Aspidonepsis, Baynesia, Brachystelma, Caralluma, Ceropegia, Chlorocyathus, Cibirhiza, Cordylogyne, Cynanchum, Dischidia, Dischidiopsis, Duvalia, Duvaliandra, Echidnopsis, Edithcolea, Eustegia, Fanninia, Fockea, Glossostelma, Hoodia, Hoya, Huernia, Huerniopsis, Ischnolepis, Larryleachia, Lavrania, Marsdenia, Matelea, Miraglossum, Notechidnopsis, Odontostelma, Ophionella, Orbea, Orbeanthus, Pachycarpus, Parapodium, Pectinaria, Periglossum, Petopentia, Piaranthus, Pseudolithos, Quaqua, Raphionacme (geophyte), Rhytidocaulon, Riocreuxia, Sarcorrhiza, Sarcostemma, Schizoglossum, Schlechterella, Stapelia, Stapelianthus, Stapeliopsis, Stathmostelma, Stenostelma, Stomatostemma, Tavaresia, Trachycalymma, Tridentea, Tromotriche, Tylophora, White-sloanea, Woodia, Xysmalobium
• Araceae: Zamioculcas
• Araliaceae: Cussonia
• Asparagaceae: Myrsiphyllum (now Asparagus)
• Asphodelaceae: Aloe (succulents and succulent geophytes), Astroloba, x Astroworthia, Bulbine (succulent geophytes, succulents, and geophytes), Bulbinella (geophyte), Chortolirion (succulent geophytes), Gasteria, Haworthia, Poellnitzia, Trachyandra (succulent geophytes and succulents),
• Asteraceae: Arctotheca, Baeriopsis, Cadiscus, 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
• Balsaminaceae: Impatiens
• Basellaceae: Anredera, Basella
• Begoniaceae: Begonia
• Boraginaceae: Heliotropium
• Brassicaceae: Heliophila, Lepidium
• Bromeliaceae: Abromeitiella
• Burseraceae: Boswellia, Bursera, Commiphora
• 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, Turbinicarpus, Uebelmannia, Weberbauerocereus, Weberocereus, Yungasocereus
• Campanulaceae: Brighamia
• Capparidaceae: Maerua
• Caricaceae: Carica, Jacarathia
• Chenopodiaceae^[5]: Atriplex, Chenopodium, Dissocarpus, Einadia, Enchylaena, Eremophea, Halopeplis, Maireana, Malacocera, Neobassia, Osteocarpum, Rhagodia, Roycea, Halosarcia, Salicornia, Salsola, Sarcocornia, Sclerochlamys, Sclerolaena, Sueda, Tecticornia, Threlkeldia
• Cochlospermaceae
• Commelinaceae: Aneilema, Callisia, Cyanotis, Tradescantia, Tripogandra
• Convolvulaceae: Ipomea, Merremia, Stictocardia, Turbina
• Crassulaceae: Adromischus, Aeonium, Afrovivella, Aichryson, Bryophyllum, Cotyledon, Crassula, Cremnophila, × Cremnosedum, Dudleya, Echeveria, Graptopetalum, Hylotelephium, Hypagophytum, Kalanchoe, Lenophyllum, Meterostachys, Monanthes, Orostachys, Pachyphytum, Perrierosedum, Phedimus, Pistorinia, Prometheum, Pseudosedum, Rhodiola, Rosularia, Sedella, Sedum, Sempervivum, Sinocrassula, Thompsonella, Tacitus, Tylecodon, Umbilicus, Villadia
• 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
• Didiereaceae: Alluaudia, Alluaudiopsis, Decaria, Didierea
• Dioscoreaceae: Dioscorea (geophytic succulent)
• Doryanthaceae: Doryanthes
• Ericaceae: Sphyrospermum
• Eriospermaceae: Eriospermum (geophyte)
• Euphorbiaceae: Cnidoscolus, Euphorbia, Jatropha, Monadenium, Pedilanthus, Synadenium
• Fabaceae: Delonix, Dolichos, Erythrina, Lotononis, Neorautanenia, Pachyrhizus, Tylosema
• Fouquieriaceae: Fouquieria
• Geraniaceae: Monsonia, Pelargonium (succulents and geophytes), Sarcocaulon
• Gesneriaceae: Aeschynanthus, Alsobia, Chirita, Codonanthe, Columnea, Nematanthus, Sinningia, Streptocarpus
• Asparagaceae: Scilloideae (geophytes, a few succulent geophytes): Albuca, Bowiea, Daubenya, Dipcadi, Drimia, Drimiopsis, Eucomis, Hyacinthus, Lachenalia, Ledebouria, Litanthus, Massonia, Merwilla, Namophila, Ornithogalum, Polyxena, Pseudogaltonia, Pseudoprospero, Resnova, Rhadamanthus, Rhodocodon, Schizobasis, Schizocarphus, Spetaea, Urginea, Veltheimia, Whiteheadia
• Hypoxidaceae (geophytes): Empodium, Hypoxis, Pauridia, Saniella, Spiloxene
• Icacinaceae: Pyrenacantha (geophyte)
• Iridaceae (geophytes): Babiana, Chasmanthe, Crocosmia, Devia, Dierama, Dietes, Duthiastrum, Ferraria, Freesia, Geissorhiza, Gladiolus, Hesperantha, Ixia, Lapeirousia, Melasphaerula, Micranthus, Moraea, Pillansia, Radinosiphon, Romulea, Sparaxis, Syringodea, Thereianthus, Tritonia, Tritoniopsis, Watsonia, Xenoscapa
• Lamiaceae: Aeollanthus, Dauphinea, Perrierastrum, Plectranthus, Rotheca, Solenostemon, Tetradenia, Thorncroftia
• Lentibulariaceae
• Loasaceae: Schismocarpus
• Loranthaceae: Actinanthella, Agelanthus, Erianthemum, Helixanthera, Moquiniella, Oncocalyx, Pedistylis, Plicosepalus, Septulina, Tapinanthus, Vanwykia
• Malvaceae: Adansonia, Cavanillesia, Ceiba, Pseudobombax
• Melastomataceae: Medinilla
• Meliaceae: Entandrophragma
• Menispermaceae: Chasmanthera, Stephania, Tinospora
• Molluginaceae: Hypertelis
• Moraceae: Dorstenia, Ficus
• Moringaceae: Moringa
• Nolanaceae: Nolana
• Nolinaceae: Beaucarnea, Calibanus, Dasylirion, Nolina
• Orchidaceae subfamily Epidendroideae Phalaenopsis
• Orchidaceae (succulents) Acampe, Aerangis, Ansellia, Bolusiella, Bulbophyllum, Calanthe, Cyrtorchis, Oberonia, Polystachya, Tridactyle, Vanilla

(succulent geophytes) Eulophia, Liparis, Oeceoclades

(geophytes) Acroliphia, Bartholina, Bonatea, Brachycorythis, Brownleea, Centrostigma, Ceratandra, Corycium, Cynorkis, Didymoplexis, Disa, Disperis, Dracomonticola, Eulophia, Evotella, Gastrodia, Habernaria, Holothrix, Huttonaea, Neobolusia, Nervilia, Plicosepalus, Pachites, Platycoryne

• Oxalidaceae (geophytes): Oxalis
• Passifloraceae: Adenia
• Pedaliaceae: Holubia, Pterodiscus, Sesamothamnus, Uncarina
• Phyllanthaceae: Phyllanthus
• Phytolaccaceae: Phytolacca
• Piperaceae: Peperomia
• Poaceae: Dregeochloa^[6]
• Portulacaceae: Amphipetalum, Anacampseros, Avonia, Calyptrotheca, Ceraria, Cistanthe, Calandrinia, Dendroportulaca, Grahamia, Lewisia, Parakeelya (this name is not accepted by the Australian State and National Herbaria)^[7], Portulaca, Portulacaria, Schreiteria, Talinella, Talinum
• Rubiaceae: Anthorrhiza, Anthospermum, Hydnophythum, Hydrophylax, Myrmecodia, Myrmephythum, Phylohydrax, Squamellaria
• Ruscaceae: Cordyline, Dracaena, Sansevieria
• Sapindaceae: Erythrophysa
• Saxifragaceae
• Sterculiaceae: Brachychiton, Sterculia
• Urticaceae: Laportea, Obetia, Pilea, Pouzolzia, Sarcopilea
• Viscaceae: Viscum
• Vitaceae: Cissus, Cyphostemma
• Xanthorrhoeaceae: Xanthorrhoea
• Zygophyllaceae: Augea, Seetzenia, Zygophyllum

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

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

See also

• Cactus and Succulent Society of America

References

External links

Look up succulent in Wiktionary, the free dictionary.

• SucculentCity.org
• Drought Smart Plants
• Cacti & Succulent Picture Gallery
• Cactus and Succulent Field Number Database
• Definition of a Succulent
• Cactus and Succulent website with plenty of information