Succulent plant

In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. It is a characteristic that is not used scientifically for the definition of most families and genera of plants because it often can be used as an accurate characteristic only at the single species level. 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. The water content of some succulent organs can get up to 90–95%.^[2] 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 that 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, as well as their ability to thrive with relatively minimal care.

Many plant families have multiple succulents species found within them (more than 25 plant families).^[3] 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, such as deserts. Succulents have the ability to thrive on limited water sources, such as mist and dew, which makes them equipped to survive in an ecosystem that contains scarce water sources.

Definition[]

By definition, succulent plants are drought resistant plants in which the leaves, stem, or roots have become more than usually fleshy by the development of water-storing tissue.^[4] Other sources exclude roots as in the definition "a plant with thick, fleshy and swollen stems and/or leaves, adapted to dry environments".^[5] This difference affects the relationship between succulents and "geophytes" – plants that survive unfavorable seasons as a resting bud on an underground organ.^[6] 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.^[7] Nor are all succulents xerophytes, since plants such as Crassula helmsii are both succulent and aquatic.^[8]

Some who grow succulents as a hobby may use the term in a different way from botanists. In horticultural use, the term succulent regularly excludes cacti. For example, Jacobsen's three volume Handbook of Succulent Plants does not include cacti.^[9] Many books covering the cultivation of these plants include "cacti and succulents" as the title or part of the title.^[10][11][12] However, in botanical terminology, cacti are succulents,^[4] but not the reverse as many succulent plants are not cacti. Cacti bear true spines and appear only in the New World (the Western Hemisphere), and through parallel evolution similar looking plants evolved in completely different plant families in the Old World without spines, a distinct organ structure.

A further difficulty for general identification is that plant families (the genus) are neither succulent nor non-succulent and contain both. 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 the succulent characteristic becomes meaningless for dividing plants into genera and families. Different sources may classify the same species differently.^[13]

Horticulturists often follow commercial conventions and may exclude other groups of plants such as bromeliads, that scientifically, are considered succulents.^[14] A practical horticultural definition has become "a succulent plant is any desert plant that a succulent plant collector wishes to grow", without any consideration of scientific classifications.^[15] Commercial presentations of "succulent" plants will present those that customers commonly identify as such. Plants offered commercially then as "succulents" (such as hen and chicks), will less often include geophytes (in which the swollen storage organ is wholly underground), but will include plants with a caudex,^[16] that is a swollen above-ground organ at soil level, formed from a stem, a root, or both.^[6]

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 may create 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)^[17]
• very impervious outer cuticle (skin)^[17]
• fast wound sealing and healing ^[18]
• mucilaginous substances, which retain water abundantly^[17]

Habitat[]

Other than Antarctica, succulents can be found within each continent. While it is often thought that most succulents come from dry areas such as steppes, semi-desert, and desert, the world's driest areas do not make for proper succulent habitats. This is a result mainly due to the difficulty such low growing plants or seedlings would have to thrive in environments where they could easily be covered by sand.^[19] Australia, the world's driest inhabited continent, hosts very few native succulents due to the frequent and prolonged droughts^{[citation needed]}. Even Africa, the continent with the most native succulents, does not host many of the plants in its most dry regions.^[20] However, while succulents are unable to grow in these harshest of conditions, they are able to grow in conditions that are uninhabitable by other plants. In fact, many succulents are able to thrive in dry conditions, and some are able to last up to two years without water depending on their surroundings and adaptations.^[21] Occasionally, succulents may occur as epiphytes, growing on other plants with limited or no contact with the ground, and being dependent on their ability to store water and gaining 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. Potted succulents are able to grow in most indoor environments with minimal care.^[22]

Families and genera[]

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There are approximately sixty different plant families that contain succulents.^[23] Plant orders, families, and genera in which succulent species occur are listed below.

Order Alismatales

• Araceae: Zamioculcas

Order Apiales

• Apiaceae:^[24] Azorella, Crithmum
• Araliaceae: Cussonia

Order Asparagales

• Amaryllidaceae (geophytes): Amaryllis, Boophone, Clivia, Crinum, Cryptostephanus, Cyrtanthus, Haemanthus, Rauhia, Scadoxus, Stenomesson
• Asparagaceae
  • Agavoideae: Agave, Beschorneria, Furcraea, Hesperaloe, Hesperoyucca, Manfreda, Polianthes, Yucca
  • Lomandroideae: Cordyline
  • Nolinoideae: Beaucarnea, Calibanus, Dasylirion, Dracaena, Nolina
  • 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, Gonialoe, Haworthia, Trachyandra (succulent geophytes and succulents),
  • subfamily Xanothorrhoeoidae: Xanthorrhoea

Order Asterales

• Asteraceae: Arctotheca, Baeriopsis, Chrysanthemoides, Coulterella, Crassocephalum, Curio, Didelta, Emilia, Eremothamnus, Gymnodiscus, Gynura, (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,
• Moringaceae: Moringa

Order Caryophyllales

• Aizoaceae: Corbichonia, Gisekia, , Limeum, , Saphesia
  • subfamily : Acrosanthes, Aizoanthemum, Aizoon, Galenia, Gunniopsis, , Tetragonia
  • subfamily (syn. Mesembryanthemaceae^[25]): Aptenia, Aridaria, , Brownanthus, Calamophyllum, , Conophytum, , Erepsia, , Hartmanthus, Hymenogyne, , Mesembryanthemum, Phiambolia, , , , Ruschiella, , Sceletium,
  • subfamily :
    • tribe : Apatesia, Carpanthea, , Conicosia, Hymenogyne, Saphesia, Skiatophytum
    • tribe Dorotheantheae: Aethephyllum Cleretum Dorotheanthus
    • tribe : Acrodon, Aloinopsis, Amphibolia, Antegibbaeum, Antimima, , Argyroderma, Astridia, Bergeranthus, , Braunsia, Brianhuntleya, Carpobrotus, Carruanthus, Cephalophyllum, Cerochlamys, Chasmatophyllum, Cheiridopsis, Circandra, Conophytum, , Cylindrophyllum, Delosperma, Dicrocaulon, Didymaotus, Dinteranthus, Diplosoma, Disphyma, Dracophilus, Drosanthemum, Eberlanzia, Ebracteola, Enarganthe, Erepsia, Esterhuysenia, Faucaria, Fenestraria, Frithia, Gibbaeum, Glottiphyllum, Hallianthus, Hereroa, , , Jacobsenia, Jensenobotrya, Jordaaniella, Juttadinteria, Khadia, Lampranthus, Lapidaria (plant), Leipoldtia, Lithops, Machairophyllum, Malephora, Mestoklema, Meyerophytum, Mitrophyllum, Monilaria, Mossia, Muiria, Namaquanthus, Namibia, Nananthus, , Neohenricia, Octopoma, , Oophytum, , Orthopterum, Oscularia, Ottosonderia, Pleiospilos, Polymita, Psammophora, Rabiea, Rhinephyllum, Rhombophyllum, Ruschia, , Ruschianthus, Schlechteranthus, Schwantesia, Scopelogena, Smicrostigma, Stayneria, Stoeberia, Stomatium Tanquana Titanopsis, Trichodiadema, Vanheerdea, Vanzijlia, Vlokia, Wooleya, Zeuktophyllum
  • subfamily Sesuvioideae: , Sesuvium, Trianthema, Tribulocarpus, Zaleya
• Amaranthaceae:
  • subfamily Amaranthoideae:
  • subfamily Chenopodioideae (family Chenopodiaceae):^[26]) Atriplex, Chenopodium, Dissocarpus, Einadia, Enchylaena, Eremophea, Halopeplis, Maireana, Malacocera, Neobassia, Osteocarpum, Rhagodia, Roycea, Halosarcia, Salicornia, Salsola, Sarcocornia, , 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, , Didierea
• Molluginaceae: Hypertelis
• Phytolaccaceae: Phytolacca
• Portulacaceae: Amphipetalum, Anacampseros, , Calyptrotheca, Ceraria, Cistanthe, Calandrinia, Dendroportulaca, Grahamia, Lewisia, ,^[27] Portulaca, Portulacaria, Schreiteria, , 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, , , Fevillea, , Gynostemma, Halosicyos, , , Lagenaria, Marah, Momordica, Neoalsomitra, , Parasicyos, , Telfairia, Trochomeria, Trochomeriopsis, Tumamoca, Xerosicyos, Zehneria,

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, , Trichocaulon, Tylophora, Woodia, Xysmalobium
    • tribe :
      • subtribe : Asclepias,
      • subtribe : Sarcostemma,
      • subtribe : Matelea,
    • tribe Maxillarieae:
      • subtribe : Rudolfiella
    • tribe Stapelieae: Angolluma, Caralluma, Desmidorchis, Duvalia, Echidnopsis, Edithcolea, Frerea, Hoodia, Huernia, Huerniopsis, Larryleachia, Notechidnopsis, Orbea (plant), Orbeopsis, Piaranthus, Pachycymbium, Pectinaria, Pseudolithos, , Quaqua, Rhytidocaulon, Stapelia, Stapelianthus, Stapeliopsis, Tavaresia, Tridentea, Tromotriche, Whitesloanea
  • subfamily Periplocoideae:
    • tribe : 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^[28]

Order Ranunculales

• Menispermaceae: Chasmanthera, Stephania, Tinospora

Order Rosales

• Moraceae: Dorstenia, Ficus
• Urticaceae: Laportea, Obetia, Pilea, Pouzolzia,

Order Santalales

• Loranthaceae: Actinanthella, Agelanthus, Erianthemum, Helixanthera, Moquiniella, Oncocalyx, Pedistylis, Plicosepalus, Septulina, Tapinanthus, Vanwykia
• Viscaceae (syn. Santalaceae): Viscum

Order Sapindales

• Anacardiaceae: , 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^[29]
• Saxifragaceae

Order Solanales

• Convolvulaceae: Ipomoea, Merremia, Stictocardia,
• Solanaceae: Nolana

Order Vitales

• Vitaceae: Cissus, Cyphostemma

Order Zygophyllales

• Zygophyllaceae: Augea, Seetzenia, Zygophyllum

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

There also are some succulent gymnosperms:

Order Pinales

• Cheirolepidiaceae:

, , ,

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 and their native habitat:^{[citation needed]}

Family or subfamily	Succulent #	Modified parts	Distribution
Agavoideae	300	Leaf	North and Central America
Cactaceae	1600	Stem (root, leaf)	The Americas
Crassulaceae	1300	Leaf (root)	Worldwide
Aizoaceae	2000	Leaf	Southern Africa, Oceania, Chile
Apocynaceae	500	Stem	Africa, Arabia, India, Australia
Asphodelaceae	500+	Leaf	Africa, Madagascar, Australia
Didiereaceae	11	Stem	Madagascar (endemic)
Euphorbiaceae	> 1000	Stem or leaf or root	Australia, Africa, Madagascar, Asia, the Americas, Europe
Portulacaceae	~500	Leaf and stem	The Americas, Australia, Africa
Cheirolepidiaceae	4, maybe more	Leaf	Worldwide, except Antarctica

Cultivation[]

Succulents are favored as houseplants for their attractiveness and ease of care. If properly potted, succulents require little maintenance to survive indoors.^[30] Succulents are very adaptable houseplants and will thrive in a range of indoor conditions.^[31] For most plant owners, over-watering and associated infections are the main cause of death in succulents.^[32]

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. A third method is propagation by leaf by allowing the formation of a callus. During this method, a bottom leaf is fully removed from the plant often by twisting or cutting. The leaf then dries out and a callus forms preventing the leaf from absorbing too much moisture and thus rotting. This method typically takes up to a few weeks to produce healthy roots that would eventually create new plants.^[33] The vegetative propagation can be different according to the species.^[34]

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.