A cactus is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word "cactus" derives, through Latin, from the Ancient Greek κάκτος, kaktos, a name used by Theophrastus for a spiny plant whose identity is not certain. Cacti occur in a wide range of sizes. Most cacti live in habitats subject to at least some drought. Many live in dry environments being found in the Atacama Desert, one of the driest places on earth. Cacti show many adaptations to conserve water. All cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. Most species of cacti have lost true leaves, retaining only spines, which are modified leaves; as well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of leaves, enlarged stems carry out photosynthesis.
Cacti are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north—except for Rhipsalis baccifera, which grows in Africa and Sri Lanka. Cactus spines are produced from specialized structures called areoles, a kind of reduced branch. Areoles are an identifying feature of cacti; as well as spines, areoles give rise to flowers, which are tubular and multipetaled. Many cacti have short growing seasons and long dormancies, are able to react to any rainfall, helped by an extensive but shallow root system that absorbs any water reaching the ground surface. Cactus stems are ribbed or fluted, which allows them to expand and contract for quick water absorption after rain, followed by long drought periods. Like other succulent plants, most cacti employ a special mechanism called "crassulacean acid metabolism" as part of photosynthesis. Transpiration, during which carbon dioxide enters the plant and water escapes, does not take place during the day at the same time as photosynthesis, but instead occurs at night.
The plant stores the carbon dioxide it takes in as malic acid, retaining it until daylight returns, only using it in photosynthesis. Because transpiration takes place during the cooler, more humid night hours, water loss is reduced. Many smaller cacti have globe-shaped stems, combining the highest possible volume for water storage, with the lowest possible surface area for water loss from transpiration; the tallest free-standing cactus is Pachycereus pringlei, with a maximum recorded height of 19.2 m, the smallest is Blossfeldia liliputiana, only about 1 cm in diameter at maturity. A grown saguaro is said to be able to absorb as much as 200 U. S. gallons of water during a rainstorm. A few species differ in appearance from most of the family. At least superficially, plants of the genus Pereskia resemble other trees and shrubs growing around them, they have persistent leaves, when older, bark-covered stems. Their areoles identify them as cacti, in spite of their appearance, too, have many adaptations for water conservation.
Pereskia is considered close to the ancestral species from. In tropical regions, other cacti grow as forest epiphytes, their stems are flattened leaf-like in appearance, with fewer or no spines, such as the well-known Christmas cactus or Thanksgiving cactus. Cacti have a variety of uses: many species are used as ornamental plants, others are grown for fodder or forage, others for food. Cochineal is the product of an insect. Many succulent plants in both the Old and New World – such as some Euphorbiaceae – bear a striking resemblance to cacti, may incorrectly be called "cactus" in common usage; the 1,500 to 1,800 species of cacti fall into one of two groups of "core cacti": opuntias and "cactoids". Most members of these two groups are recognizable as cacti, they have fleshy succulent stems. They have small, or transient leaves, they have flowers with ovaries that lie below the sepals and petals deeply sunken into a fleshy receptacle. All cacti have areoles—highly specialized short shoots with short internodes that produce spines, normal shoots, flowers.
The remaining cacti fall into only two genera and Maihuenia, are rather different, which means any description of cacti as a whole must make exceptions for them. Pereskia species superficially resemble other tropical forest trees; when mature, they have woody stems that may be covered with bark and long-lasting leaves that provide the main means of photosynthesis. Their flowers may have superior ovaries, areoles that produce further leaves; the two species of Maihuenia have globe-shaped bodies with prominent leaves at the top. Cacti show a wide variety of growth habits, which are difficult to divide into clear, simple categories. Arborescent cactiThey can be tree-like, meaning they have a single more-or-less woody trunk topped by several to many branches. In the genus Pereskia, the branches are covered with leaves, so the species of this genus may not be recognized as cacti. In most other cacti, the branches are more cactus-like, bare of leaves and bark, cove
Lieutenant General Balwant Singh Negi, PVSM, UYSM, YSM, SM, VSM & Bar is a former General Officer-Commanding-in-Chief, Central Command of the Indian Army who served in office from 1 December 2015 till 30 September 2018. He assumed the post after Lt General Rajan Bakshi retired and was succeeded by Lt General Abhay Krishna. Negi is an alumnus of Rashtriya Indian Military College, National Defence Academy and Indian Military Academy, he has completed the senior command course at Wellington. He holds a double MPhil in Strategic Studies and Defence Studies). Negi was commissioned into Assam Regiment on 16 December 1978, he has vast experience in Jammu & Kashmir. He has commanded a battalion on the Siachen Glacier, a brigade in Western Command, a Counter Insurgency Force in Jammu & Kashmir and Jharkhand & Bihar, XIV Corps, he has held command of many operations including Operation Meghdoot, Operation Vijay, Operation Rakshak, Operation Parakram, Operation Falcon, Operation Trident, Operations Sahayata I and II.
He has held staff appointments including He has held Colonel General Staff of an Infantry Division in Jammu & Kashmir during Operation Parakram. During 37 years of his career he has been awarded Yudh Seva Medal for Siachen in 1998, he has been awarded with General Officer Commanding-in-Chief Commendation Card and Chief of Integrated Defence Staff Commendation Card. He is an excellent sportsman with three Blues in Boxing and Gymnastics from National Defence Academy, he is a keen equestrian track and Master of Fox Hounds for Ooty Hunt Club. On a 350cc Royal Enfield Motorcycle
The Siberian Times is an English-language news website, launched in Novosibirsk, Russia in 2012. It aims to challenge people's "stereotypes, many negative and out of date," about the region, according to its editor, Svetlana Skarbo. By accounts from her former employees at East2West Limited, the site is the brainchild of Will Stewart, a British journalist who cites it as a source in his articles. According to Mashable, its stories are "allegedly real with a bit of hyperbole/Siberian fan fiction thrown in". Stories from the site are picked up in Western media, such as an article about frozen Siberian worms being reanimated after thawing out of the permafrost. Doubtfulnews.com referred to the website in 2014 as "not a reliable source for news". The story about ancient roundworms being resuscitated from the permafrost was reported by the Smithsonian website, though the claim was made by the academic journal Doklady Biological Sciences. Other Siberian Times stories have been picked up by Radio Free Europe/Radio Liberty, The Daily Telegraph, The Independent and Business Insider