Succulent Plants,
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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.
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:
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 parallel 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. This process may be confused with convergent evolution that occurs in species that are related more closely.
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 species, Opuntia, is thought 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.
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]
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 parallel 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. This process may be confused with convergent evolution that occurs in species that are related more closely.
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 species, Opuntia, is thought 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.