Like herbarium a botanic garden is also an important centre for study of plant taxonomy. It is, however, important from other aspects also, such as researches on other branches of pure and applied Botany and to serve as a beauty spot and pleasure garden for the enjoyment of general public.
As to its scientific aspects it helps directly in the study of plant taxonomy, ecology, horticulture and agriculture and indirectly in other branches of Botany. It plays an important role in the introduction and acclimatization of foreign plants, eradication and control of weeds, pollution and purification of air and water.
For study of plant morphology, ecology and taxonomy, plants from different parts of the country as well as from foreign countries are cultivated in suitable plots within the garden in similar natural habitats often created artificially.
There are conservatories for growing shade loving plants or plants of cooler or warmer countries. In temperate climates the conservatories in a botanic garden provide good opportunities for growing plants of warmer countries by controlling temperature and humidity and often reducing bright-sunlight for the shade-loving plants.
The perennial plants cultivated in a botanic garden are not planted haphazardly, but mainly arranged on a phytogeography plan, while a separate portion is left to cultivate representatives of different families of plants following some system of classification. This portion is called students’ garden.
In the phytogeography plan of arrangement the garden is divided into several plots each representing a particular country as regards to its vegetation.-Foreign plants, trees, shrubs and climbers which can easily grow in the open in the prevailing climatic condition are grown in plots allotted to different countries.
This gives the students some idea of the nature of vegetation of other countries of the world and also to study the morphological peculiarities of different types of plants and the ecological conditions for their growth. Separate sections are also created and kept reserved for growing special types of plants like Xerophytes, Halophytes, fresh-water aquatics, etc.
Another section is kept apart for observing the behaviour of plants newly introduced from some foreign countries. This is usually called the economic section or economic garden as it is the economic or otherwise ornamental plant which is usually introduced from abroad.
A nursery is always maintained in a botanic garden where seedlings are raised for planting in the garden and for distribution to other gardens and parks. Agricultural and horticultural experiments are also carried out in the nursery.
A botanic garden has an aesthetic aspect. For that purpose decorative plants are cultivated more in a botanic garden than other type of plants, and in planting trees this aspect is always kept in view. Further, several small plots are maintained to grow flowering annuals. Beautiful lawns, paths and avenues are laid throughout the garden for the enjoyment of visitors.
Small statues, bird-baths and masonry constructions are erected to decorate the garden. The pools are so arranged that they enhance the beauty of the garden. Sometimes an artificial canal is dug out inside the garden to give the idea of a streamlet. The pools and canals also serve the purpose of irrigation of the garden in addition to the cultivation of aquatic plants and for enhancing the beauty of the garden.
Separate sections are Set apart for laying out different styles of gardening, e.g., landscape garden, Japanese garden, Italian garden, etc. Trees and shrubs are pruned to give different shapes, sometimes of animals or birds.
This art of beautifying the garden is known as Tapiary, Another art in gardening is to keep trees in dwarf condition and such trees are called Bonsai trees. These are for the enjoyment of garden-lovers as well as of general public. In large gardens a separate section is often set apart to cultivate big trees to give an impression of a forest. This is called arboretum or dendrarium.
Selection of site is also important as some places are by nature a beauty spot. Undulating areas are preferred to a flat expanse; area with a natural lake or a small streamlet passing through it possesses a natural beauty of its own and can be easily converted into an ideal garden.
This, however, is not always easy, as a large area suitable for establishing a botanic garden is hard to be found. For this reason large botanic gardens have usually been established away from the cities.
Names of a few famous botanic gardens of the world are given below:
1. Royal Botanic Garden, Kew, London:
This was a private garden of the Capel family to begin with. In 1728 it was taken over on lease by Prince Frederick, Prince of Wales. From that time it came to be known as the Royal Garden and later was given to the nation by the Royal family.
It gradually developed into one of the best botanic gardens in all aspects by the efforts of the botanists and horticulturists working in the garden. It covers an area of 300 acres and has the world’s largest herbarium. The garden has different sections and several large conservatories.
Sir Joseph Dalton Hooker, author of ‘Flora of British India’ and of many other important botanical works including “Genera Plant-arum” giving a natural system of classification of flowering plants jointly with George Bentham, was once a Director of this garden, and John Hutchinson who proposed a new phylogenetic system worked in the herbarium of this garden.
2. Royal Botanic Garden, Edinburgh:
This covers an area of 50 acres. This was at the beginning a garden of medicinal herbs established in the middle of 17th century Later it developed into a botanic garden. It has a beautiful rock garden and a herbarium with a good collection of specimens from central Asia, among other things.
3. Botanical Garden, Berlin—Dahlem:
The Botanical Garden of Berlin had been situated in 2 other places before it was transferred to Dahlem in 1880. The area of the garden is 103 acres. Associated with it are the Botanical Museum and the Herbarium, both having rich collections? The garden is mainly geographically arranged while in one part arc arranged different families according to the system of classification of Engler and Prantl.
There are large conservatories, good rock-garden and several decorative pools. Prof. Adolf Engler was one of the Directors of this garden, by whose efforts the garden became one of the most important botanic gardens for the scientific arrangement and for the beautiful lay out.
4. Bundrs Garden, Vienna:
This is a large garden and one of the oldest in Europe covering an area of 400 acres. It has a fine Alpine garden with varieties of cool-climate plants collected from high mountains as well as from artic region.
5. Main Botanic Garden, Moscow:
This is the largest Botanic Garden in Europe with an area of 900 acres. It has a long line of conservatories and several tropical houses. Introduction and acclimatization of exotic trees and shrubs is one of the main features of this garden. It has .i large herbarium and good laboratory and library.
6. Nikitisky Botanic Garden, Yalta:
This is another famous and old Botanic Garden and oldest in U.S.S.R. Established in 1812 it covers an area of 272 acres. The different sections of the garden are well arranged and the Italian garden is one of the finest with pergolas and water reservoirs. It has a good herbarium of rich collection of specimens from Southern Europe and Western and Central Asia.
7. Indian Botanic Garden, Sibpur, Calcutta:
Established in 1787 mainly for cultivation of economic plants and timber trees. Col. Robert Kyd was the founder who was succeeded by Dr. William Box burgh who gave the garden a botanical shape. At present it occupies an area of 273 acres.
It is the oldest and largest botanic garden in Asia and has among other curious plants in cultivation; the Big Banyan tree, the largest tree in the world covering an area of about 15,000 sq. mtrs. The Central National Herbarium, the biggest herbarium in Asia is situated inside the garden.
8. Kebun Raya (Botanic Garden) Bogor, Java:
This is another old and famous garden being established in 1817 and covering an area of 200 acres. Among other things it has a separate section to represent a virgin rain-forest where nothing has been planted by man. It has a good herbarium and library.
9. Missouri Botanic Garden, U.S.A.:
The garden situated in the city’s suburbs covers an area of 75 acres but outside the city the Grey Summit Arboretum occupies an area of 1600 acres. It has a large dome-shaped conservatory built on geodesic principle. Collections of Orchids and succulents are excellent. It is an important centre of taxonomical work and contains a large herbarium and library.
10. Arnold Arboretum, Boston, U.S.A.:
Starting as a small garden of the Harvard University it now occupies an area of 265 acres. It contains a number of green houses and a rich collection of bonsai trees, the oldest being 175 years of age.