Doan Nguyen
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. The word succulent comes from the Latin word sucus, meaning “juice” or “sap”.
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%, such as Glottiphyllum semicyllindricum and Mesembryanthemum barkleyii. Some definitions also include roots, thus geophytes that survive unfavorable periods by dying back to underground storage organs may be regarded as succulents. The habitats of these water-preserving plants are often in areas with high temperatures and low rainfall, such as deserts, but succulents may be found even in alpine ecosystems growing in rocky soil. Succulents are characterized by their 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.
Succulents are not a taxonomic category, since the term describes only the attributes of a particular species; some species in a genus (such as Euphorbia spp) or family (such as Asphodelaceae) may be succulent, whereas others are less so or not at all. Many plant families have multiple succulent species found within them (more than 25 plant families).[4] In some families, such as Aizoaceae, Cactaceae, and Crassulaceae, most species are succulents. In horticultural use, the term 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.
Not to be confused with cactus; nearly all cacti are succulents, but not all succulents are cacti.
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. Other sources exclude roots as in the definition “a plant with thick, fleshy and swollen stems and/or leaves, adapted to dry environments”. The difference affects the relationship between succulents and “geophytes”–plants that survive unfavorable seasons as a resting bud on an underground organ. The 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 devel lents 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 includ e cacti. Many books covering the cultivation of these plants include “cacti and succulents” as the title or part of the title. However, in botanical terminology, cacti are succulents, but not the reverse as many succulent plants are not cacti. Cacti form a monophyletic group and apart from one species are native only to the New World (the Americas), but through parallel evolution similar looking plants in completely different families like the Apocynaceae evolved in the Old World.
A further difficulty for general identification is that plant families are neither succulent nor non-succulent and can 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. The succulent characteristic becomes meaningless for dividing plants into genera and families. Different sources may classify the same species differently. Species with intermediate characteristics such as somewhat fleshy leaves or stems may be described as semi-succulent.
Horticulturists often follow commercial conventions and may exclude other groups of plants such as bromeliads, that scientifically are considered succulents. 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.
Habitat
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)
• very impervious outer cuticle (skin)
• fast wound sealing and healing
• mucilaginous substances, which retain water abundantly
Conservation
In South Africa, several species have been threatened with extinction due to poaching from the wild for the black market and mining related activities. The plants are mainly sold to collectors in Asian countries, where there has been a high demand for them. It is illegal since 1974 to be in possession of protected succulents such as the Conophytum without authorisation in the Western Cape and Northern Cape, the two South African provinces where they grow.
Families and genera
There are approximately sixty different plant families that contain succulents.
I have a thing with these little plants. They are tough. They are multivarious. They are my friends.
Resource: en.wikipedia.org/wiki/Succulent_plant
Images: Doan Nguyen-Kate
I love succulent plants.
