Most are at least partly open to the public, and may offer guided tours, educational displays, art exhibitions, book rooms, open-air theatrical and musical performances, and other entertainment.In principle, their role is to maintain documented collections of living plants for the purposes of scientific research, conservation, display, and education, although this will depend on the resources available and the special interests pursued at each particular garden.Over the years, botanical gardens, as cultural and scientific organisations, have responded to the interests of botany and horticulture.Nowadays, most botanical gardens display a mix of the themes mentioned and more; having a strong connection with the general public, there is the opportunity to provide visitors with information relating to the environmental issues being faced at the start of the 21st century, especially those relating to plant conservation and sustainability.The following definition was produced by staff of the Liberty Hyde Bailey Hortorium of Cornell University in 1976.A botanical garden is a controlled and staffed institution for the maintenance of a living collection of plants under scientific management for purposes of education and research, together with such libraries, herbaria, laboratories, and museums as are essential to its particular undertakings.Each botanical garden naturally develops its own special fields of interests depending on its personnel, location, extent, available funds, and the terms of its charter.The botanic garden may be an independent institution, a governmental operation, or affiliated to a college or university.It is not merely a landscaped or ornamental garden, although it may be artistic, nor is it an experiment station or yet a park with labels on the plants.A contemporary botanic garden is a strictly protected natural urban green area, where a managing organization creates landscaped gardens and holds documented collections of living plants and/or preserved plant accessions containing functional units of heredity of actual or potential value for purposes such as scientific research, education, public display, conservation, sustainable use, tourism and recreational activities, production of marketable plant-based products and services for improvement of human well-being.Worldwide, there are now about 1800 botanical gardens and arboreta in about 150 countries (mostly in temperate regions) of which about 550 are in Europe (150 of which are in Russia)[citation needed], 200 in North America,[6] and an increasing number in East Asia.Historically, botanical gardens exchanged plants through the publication of seed lists (these were called Latin: Indices Seminae in the 18th century).This system continues today, although the possibility of genetic piracy and the transmission of invasive species has received greater attention in recent times.[14] Later, in the 18th century, they became more educational in function, demonstrating the latest plant classification systems devised by botanists working in the associated herbaria as they tried to order these new treasures.Then, in the 19th and 20th centuries, the trend was towards a combination of specialist and eclectic collections demonstrating many aspects of both horticulture and botany.The idea of "scientific" gardens used specifically for the study of plants dates back to antiquity.Near-eastern royal gardens set aside for economic use or display and containing at least some plants gained by special collecting trips or military campaigns abroad, are known from the second millennium BCE in ancient Egypt, Mesopotamia, Crete, Mexico and China.[18] In about 2800 BCE, the Chinese Emperor Shen Nung sent collectors to distant regions searching for plants with economic or medicinal value.Ibn Bassal then founded a garden in Seville, most of its plants being collected on a botanical expedition that included Morocco, Persia, Sicily, and Egypt.[24][25] There is some debate among science historians whether this garden was ordered and scientific enough to be considered "botanical", and suggest it more appropriate to attribute the earliest known botanical garden in Europe to the botanist and pharmacologist Antonius Castor, mentioned by Pliny the Elder in the 1st century.Many of these were found in British gardens even though they only occurred naturally in continental Europe, demonstrating earlier plant introduction.[nb 2] Here the physicians (referred to in English as apothecaries) delivered lectures on the Mediterranean "simples" or "officinals" that were being cultivated in the grounds.Student education was no doubt stimulated by the relatively recent advent of printing and the publication of the first herbals.For example, Asian introductions were described by Carolus Clusius (1526–1609), who was director, in turn, of the Botanical Garden of the University of Vienna and Hortus Botanicus Leiden.Clusius laid the foundations of Dutch tulip breeding and the bulb industry, and he helped create one of the earliest formal botanical gardens of Europe at Leyden where his detailed planting lists have made it possible to recreate this garden near its original site.His Exoticorum libri decem (1605) is an important survey of exotic plants and animals that is still consulted today.[34] The inclusion of new plant introductions in botanic gardens meant their scientific role was now widening, as botany gradually asserted its independence from medicine.In the mid to late 17th century, the Paris Jardin des Plantes was a centre of interest with the greatest number of new introductions to attract the public.With the increase in maritime trade, ever more plants were being brought back to Europe as trophies from distant lands, and these were triumphantly displayed in the private estates of the wealthy, in commercial nurseries, and in the public botanical gardens.[36] Industrial expansion in Europe and North America resulted in new building skills, so plants sensitive to cold were kept over winter in progressively elaborate and expensive heated conservatories and glasshouses.The 18th century was marked by introductions from the Cape of South Africa – including ericas, geraniums, pelargoniums, succulents, and proteaceous plants – while the Dutch trade with the Dutch East Indies resulted in a golden era for the Leiden and Amsterdam botanical gardens and a boom in the construction of conservatories.From the 1770s, following the example of the French and Spanish, amateur collectors were supplemented by official horticultural and botanical plant hunters.At this time, British horticulturalists were importing many woody plants from Britain's colonies in North America, and the popularity of horticulture had increased enormously, encouraged by the horticultural and botanical collecting expeditions overseas fostered by the directorship of Sir William Jackson Hooker and his keen interest in economic botany.[41] At the end of the 18th century, Kew, under the directorship of Sir Joseph Banks, enjoyed a golden age of plant hunting, sending out collectors to the South African Cape, Australia, Chile, China, Ceylon, Brazil, and elsewhere,[42] and acting as "the great botanical exchange house of the British Empire".In this century, botanical gardens effectively dropped their medicinal function in favour of scientific and aesthetic priorities, and the term "botanic garden" came to be more closely associated with the herbarium, library (and later laboratories) housed there than with the living collections – on which little research was undertaken.The late 18th and early 19th centuries were marked by the establishment of tropical botanical gardens as a tool of colonial expansion (for trade and commerce and, secondarily, science) mainly by the British and Dutch, in India, South-east Asia and the Caribbean.[47] This was also the time of Sir Joseph Banks's botanical collections during Captain James Cook's circumnavigations of the planet and his explorations of Oceania, which formed the last phase of plant introduction on a grand scale.This was followed by the West Indies (Botanic Gardens St