A caltrop (also known as caltrap, galtrop, cheval trap, galthrap, galtrap, calthrop, crow's foot) is an antipersonnel weapon made up of two or more sharp nails or spines arranged in such a manner that one of them always points upward from a stable base (for example, a tetrahedron). Caltrops were part of defenses that served to slow the advance of horses, war elephants, and human troops. They were said to be particularly effective against the soft feet of camels. In more modern times, caltrops are used against wheeled vehicles with pneumatic tires.
The modern name "caltrop" is derived from the Latin calcitrapa (foot-trap). The synonymous Latin word tribulus gave rise to the modern Latin name of a plant offering similar hazards to sandaled or bare feet, Tribulus terrestris (Zygophyllaceae), whose spiked seed case can injure feet and puncture tires. This plant can also be compared to the starthistle, Centaurea calcitrapa, which is sometimes called the "caltrop". A water plant with similarly-shaped spiked seeds is called the "water caltrop", Trapa natans.
The water caltrop, water chestnut, buffalo nut, bat nut, devil pod, Singhara (Hindi: सिंघाडा)سنگھارا (Urdu) or Pani-fol (Hindi: पानीफल) is any of three extant species of the genus Trapa: Trapa natans, T. bicornis and the endangered Trapa rossica. The species are floating annual aquatic plants, growing in slow-moving water up to 5 meters deep, native to warm temperate parts of Eurasia and Africa. They bear ornately shaped fruits, which in the case of T. bicornis resemble the head of a bull, each fruit containing a single very large starchy seed. T. natans and T. bicornis have been cultivated in China and India for at least 3,000 years for the edible seeds.
Military science is the theory, method, and practice of producing military capability in a manner consistent with national defense policy.]citation needed[ Military science serves to identify the strategic, political, economic, psychological, social, operational, technological, and tactical elements necessary to sustain relative advantage of military force; and to increase the likelihood and favorable outcomes of victory in peace or during a war. Military scientists include theorists, researchers, experimental scientists, applied scientists, designers, engineers, test technicians, and other military personnel.
Military personnel obtain weapons, equipment and training to achieve specific strategic goals. Military science is also used to establish enemy capability as part of technical intelligence.
The Chinese water chestnut (Eleocharis dulcis; synonyms E. equisetina, E. indica, E. plantaginea, E. plantaginoides, E. tuberosa, E. tumida), more often called simply the water chestnut, is a grass-like sedge grown for its edible corms. The water chestnut is actually not a nut at all, but an aquatic vegetable that grows in marshes, underwater in the mud. It has tube-shaped, leafless green stems that grow to about 1.5 metres. The water caltrop, which is also referred to by the same name, is unrelated and often confused with the water chestnut.
The small, rounded corms have a crisp white flesh and can be eaten raw, slightly boiled, or grilled, and are often pickled or tinned. They are a popular ingredient in Chinese dishes. In China, they are most often eaten raw, sometimes sweetened. They can also be ground into a flour form used for making water chestnut cake, which is common as part of dim sum cuisine. They are unusual among vegetables for remaining crisp even after being cooked or canned, because their cell walls are cross-linked and strengthened by certain phenolic compounds, like oligomers of ferulic acid. This property is shared by other vegetables that remain crisp in this manner, including the tiger nut and lotus root.
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells in an effort to produce energy, maintain life, or stimulate growth.
Historically, people secured food through two methods: hunting and gathering, and agriculture. Today, most of the food energy consumed by the world population is supplied by the food industry.
An area denial weapon is a device used to prevent an adversary from occupying or traversing an area of land. The specific method used does not have to be totally effective in preventing passage (and sometimes is not) as long as it is sufficient to severely restrict, slow down, or endanger the opponent. Most area denial weapons pose long-lasting risks to anyone entering the area, specifically to civilians, and thus are often controversial.
In the 18th century, Spanish bayonet (probably the locally-common species Yucca aloifolia) was planted around the fortifications of St. Augustine, Florida to discourage penetration by both man and beast.
Invasive species, also called invasive exotics or simply exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions.
Because of the variability of its definition, and because definitions are often from a socioeconomic perspective, the phrase invasive species is often criticized as an imprecise term for the scientific field of ecology. This article concerns the first two definitions; for the third, see Introduced species.