The Encyclopedia Americana (1920)/Botanical Gardens

From Wikisource
Jump to navigation Jump to search

Edition of 1920. See also Botanical garden on Wikipedia, and the disclaimer.

BOTANICAL GARDENS. The term botanical garden is used to designate a limited area of ground on which is grown a collection of plants including a large number of species brought together to subserve scientific, educational, æsthetic or economic purposes. In the broadest sense, it is a museum of plants and one of its chief ends is to represent, by means of living specimens so far as possible, the principal types of vegetation of the earth. It is impossible to cultivate more than a few thousand species on any given area under the natural conditions of soil and climate, and the open-air plantations are generally supplemented by collections grown under shelter, in glass houses and in specially prepared soils. It has been found practicable to grow in this manner as many as 12,000 or 15,000 species of the higher plants in the botanical gardens at Saint Louis and New York, at Kew, near London, England, and at Berlin, Germany. A proper selection of this number may be made to represent somewhat fairly the principal forms of plants, which include about 250,000 species. That is to say, it is possible to grow in one place about one species out of every 17 in existence.

Living plants cultivated in the open air are most suitably arranged in plantations according to their general habit and in such manner as to show their general relationships. Then special groups are often made of certain families, such as the conifers, the willows and poplars, the grasses, ferns or mosses. The most common arrangement of plantations includes the herbaceous grounds, the aquatic plants, alpinum, viticetum, fruticetum, arboretum and economic plantations. Some institutions bring together collections for the purpose of illustrating the local flora or the flora of any given geographical district

The herbaceous plantations are intended to include the representatives of small soft-bodied plants which die down to the soil during the winter or resting season, and which may or may not have a perennial underground stem-formation of some kind. Many of the species are annuals and must be grown from seeds every year.

The pools for aquatic plants are arranged to afford suitable means for the culture of forms which float or root in ponds and streams of fresh water, and include a wide variety, such as the water-lily, pondweeds, Philotria, water-hyacinth, etc.

An alpinum is a special plantation generally arranged to afford means of cultivation of species from cold climates on mountain-tops or in higher latitudes. Plantations of this kind are often termed rockeries, and are in the form of a ridge or hill covered with boulders. In such plantations precautions must be taken to give lime-loving plants a place among limestone rocks, and with the necessary low temperatures.

The viticetum is a plantation devoted to the cultivation of climbing and trailing vines, and may take almost any form demanded by the exigencies of practical gardening. Among the necessary features are trellises or supports for twining and tendril climbing forms.

The fruticetum includes all woody perennial plants which do not form a central trunk six feet in height, and which are therefore not trees. These are most effectively grouped when the individuals of the separate species are placed in the ground separately in a scheme of general arrangement by which every plant may be inspected from all sides and is unshaded by its neighbors.

The arboretum includes trees, and these may be variously arranged, singly or in groups, always with respect to their mutual relationship. On account of their great size and comparatively slow growth and greater permanency, the placing of trees in any given landscape scheme in a garden is attended to with the greatest care.

The economic plantations may include useful plants arranged according to their relationships, and grouped according to the use or nature of the derivative. Thus a division may be made in which only species used for medicine, foods or clothing are included, or a division may be made to include plants which yield starches, oils, gums and resins.

Special plantations of selected families must depend for their constituency upon the location of the garden. Thus it would be possible to form a collection of palms in a tropical garden and one of pines or willows in a temperate climate. Geographical plantations may take any given district by variously arranged plantations.

Still another group of plantations is being made in some gardens to illustrate types of habit and structure. Some of the principal groups to be illustrated in this manner are parasites, which draw nourishment from the living bodies of other organs; saprophytes, which live on decaying organic matter; xerophytes, plants adapted to living under the driest conditions; plants with structures serving as a protection against animals. Forms of propagation and reproduction, methods of dissemination of spores and seeds, etc., also serve as subjects to be illustrated by separate groups.

The collections grown under shelter and in conservatories are generally grouped in such manner that species are partly assembled with regard to their climatic requirements, and partly according to their relationships. Thus a house may be devoted to tropical plants, or to temperate plants, or may contain only orchids, palms, ferns, cacti or succulents, or other special groups.

The part of the vegetable kingdom which may not be cultivated may be represented in a museum by dried specimens, material in preserving-fluids and dissections of various kinds. Here again the arrangement may be upon the basis of natural relationship, or upon the basis of economic usefulness. The species which formed the vegetation of the previous geological periods are represented by fossil specimens, completing the history of the plant-world so far as it is known, and yielding suggestions as to the descent of the present types.

Two general educational purposes are served by an institution of this character. Its collections are arranged to present information on the form, relationship, mode of life, habit and general biological character of the principal types of vegetation, in such manner as to be capable of comprehension by persons unacquainted with the technical aspects of the subject. Further interpretation of such facts may be made by means of books, journals, lectures, etc., devoted to this branch of work and study.

The material accumulated for the exploitation of popular knowledge of plants also affords an excellent basis for the induction of students into the more strictly scientific aspects of botany; and when such material is supplemented by laboratories furnished with apparatus, microscopes and other instruments of precision, the activities of these students may be carried beyond the frontiers of the subject into the investigation and discovery of new facts and phenomena. This extension of the boundaries of knowledge concerning the plant-world may be carried on to advantage only when a library is at hand containing all of the more important literature bearing upon the subject.

Botanical gardens owe their origin to the needs of medical science, in accordance with which species showing valuable medicinal properties were grown in convenient places.

The first authentic record of the introduction of medicinal plants into cultivated plots of ground dates no farther back than the time of the elder Pliny (23-79 A.D.), who writes of the garden Antonius Castor, at Rome, in which were grown a large number of medicinal plants. This step, however, may have been taken much earlier by the Greeks, Chinese or Mexicans. Later the Benedictine monks of northern Italy paid great attention to the growing of remedial herbs, and devoted an important proportion of the monastery gardens to this purpose. This practice was also carried beyond the Alps, and in 1020 a garden was in existence at the monastery of Saint Gall, in Switzerland, not far from Lake Constance, which contained 16 plots occupied by medicinal plants. A garden of this character was founded 1309 at Salerno, and another at Venice 1330.

The 16th and 17th centuries witnessed the foundation of many gardens in England, France, Germany, Holland and Sweden, some of which have had a continuous existence to this day. The garden of Bologna was founded 1568; Leyden, 1577; Leipzig, 1579; Montpellier, 1596; Paris, 1597. The last named was organized for the determination of “what variations were possible in the style of bouquets worn at the royal courts.” Then followed the establishment of the gardens at Giessen, 1605; Strasburg, 1620; Jena, 1629; Oxford, 1632; Upsala, 1667; Chelsea, 1680.

The number of these institutions at the present time is nearly 300, only a few of which, however, are devoted to the more important purposes named above. Many botanical gardens are merely municipal parks in which some attempt is made to exhibit special groups of plants, and are devoted chiefly to floriculture. Others are almost entirely experiment stations for the exhibition and testing of economic species, while still others find their chief usefulness as an aid in teaching botany in schools and colleges. For the educational value of botanical gardens, consult Monroe, ‘Cyclopedia of Education.’

Daniel Trembly MacDougal,
Department of Botanical Research, Carnegie Institution, Washington.