Succulence or Succulency  [ Botany ]
Adjective: Succulent  Synonym: Juicy   
Adverb: Succulently

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(From Latin "succulentus" [ succus =  juice] "juicy”, "moistly ")

For example: a succulent plant (such an Agave or a Cactus) or a succulent plant part ( such as a succulent leaf, stem or fruit)

 

A succulent is a (usually) nonwoody plant ( also defined Primary  stem succulent) that has specialized fleshy, soft and juicy tissues designed for the conservation of water. The enlargement is usually due to the greater amount of the parenchyma tissue that act as water reservoirs. This tissues guarantees a temporary storage of utilizable water, which makes the plant temporarily independent from external water supply. The water storage tissue may be found in the stem, leaves, or roots depending on the species.   Stem succulents,  leaf succulents, and  root succulents are types of growth forms.
(Haworthia emelyae) Leaf and root succulence	Classifying plants as succulent or nonsucculent is anyway quite arbitrary , many popular books on succulents are all vague at defining what makes a plant a succulent. For example, a lot of popular publications on succulents often ignore clearly succulent plants such as many orchids and bromeliads simply because most succulent collectors don't grow them. A commons popular classification also differentiate   the cacti (Family: Cactaceae) from the “succulents” that encompass all the other succulent plants.	(Sulcorebutia rauschii) Stem succulence
Although all plants store water, succulents are especially adapted to store water for longer periods.  This allows them to survive in arid environments during times of drought and most are xerophytes (plants preferring dry climates, such as cactus or sedum). But some are halophytes (adapted for living in salty soils where water retention is a problem or in coastal areas where the succulent tissue protects the plants from the harsh salty environment.), other are geophytes (plants with their perennating organs below ground, colloquially called "bulbs" in horticulture). In reality succulents can exist in all climates and in rainfall regions too. Several succulent are also epiphytes and come from tropical rainforests with very high rainfall and many succulent plants enjoy very favourable growing climates for most of the year and only posses a succulent nature to survive the few short months when rainfall becomes very low.
(Euphorbia obesa) Having a large internal volume for storage but minimum surface area is also important to prevent drying up.	During the day, the habitat of most succulent xerophytes is rather hot. However it is cool at night when the succulents can respire. In the morning, often the abundant dewfall of arid lands helps the plants to survive. Some succulents try to take up as much moisture from the dew as possible by having large surface area covered by long hair. Many succulents often have waxy outer layers that allow the plants to retain water well. Having a large internal volume for storage but minimum surface area is also important to prevent drying up. CAM photosynthesis is also a common feature found in many succulents for water conservation.	(Sulcorebutia gerosenilis) The long hairs of same succulents help to take up as much moisture from the dew
Succulence is a feature due to convergent evolution and is not necessarily an indication of genetic relationship. There are succulents in many unrelated families. However, for some families, most members are succulent; for example the Cactaceae, Agavaceae, Aizoaceae, and Crassulaceae.