The principle upon which all genuine Botanic gardens are established is the acquisition of plant materials for teaching, research and public amenity. Conservation forms part of these functions and the scope for conservation in the Dundee Garden is increasing. The tradition of using botanic gardens to illustrate the supposed taxonomic or evolutionary relationships of plants has never formed part of the policy of this garden.
The major areas of teaching and research are concentrated on the physiological function of plants, their survival strategies, ecology, symbiotic and family relationships. The Garden, therefore, has no brief to make large collections of plants based on purely aesthetic considerations or even on grounds of botanical curiosity. Indeed, the words of John Lindley, uttered in 1830 when he was invited to examine the role of the Botanic Gardens at Kew are always kept in mind when selecting plants for this botanic garden:
It is little better than a waste of time and money to maintain it in its present form if it fulfils no intelligible purpose except that of sheltering a large quantity of rare and valuable plants.
In short, the ideal is that each plant grown can be justified by its contribution to the Garden's wider aims and objectives.
Native Plant Communities
One of the most important features of the Garden is the Native Plant Communities Unit. Here, a series of plant associations has been established to represent types of vegetation that can be found in Britain. Sited in a layout running north to south are representatives of the mountain and uplands areas, dwarf scrub, pine and birch forest, ash wood, oak and beech forest and, at the lowest point, a nutrient-rich pool. These are linked by a burn, which is fed from a spring in the North West corner of the Garden. The woody plant elements are now sufficiently mature to allow the introduction beneath the trees of the associated field layers and the woodlands are already proving a useful teaching resource for students, school pupils and the general public.
Unlike a taxonomic layout, where plants are assembled in un-natural groupings that show supposed evolutionary relationships, the layout of the Botanic Garden respects the real nature of vegetation, thereby promoting familiarity with native plants from all over the British Isles, as well as providing a useful guide to their ecology. Although not a substitute for field study, this is vital where the curriculum is already crowded. Furthermore, it has also proved an economical method for growing environmentally demanding plants, since landscape gardeners, and environmentalists responsible for the rehabilitation of the countryside, have found the methods of establishment and management of this Unit to be of great interest and utility.
The remainder of the Garden is given over to layouts of exotic plants with a similar ecological and geographical basis. Already there are noteworthy collections of conifers, Australasian, Asian, North American and Mediterranean plants, primitive flowering plants, and aquatics. The garden's favourable climate can be judged by the successful cultivation of plants which would normally be considered too tender to survive in the east of Scotland. Regnellidium diphyllum, a floating aquatic fern from Rio del Sul in Brazil, is an example of an unusual plant which thrives in the Garden. Normally very difficult to grow, it seems to luxuriate not only in the temperate and tropical glasshouses but also in one of the necklace ponds which feed Loch Machar - the exotic plant pool near the Visitors' Centre, built with funds provided by Alex Machar, a former Curator of Grounds in the University, who was the first to realise the potential of the site.
Other collections include examples of physiological adaptations to wet, dry, tropical and temperate zones, and of the strategies that plants have evolved to overcome hostile conditions.