What is a botanic garden?

Traditionally, botanic gardens are defined as places were a wide variety of documented living plants are cultivated for ornamental purposes, scientific research and education. The world’s first botanic gardens were the university gardens of Italy in the 16th and 17th centuries (fig.1). These gardens were purely for the academic study of medicinal plants.

For over five centuries, botanic gardens and herbaria around the world have been generating resources and expertise and teaching us most of what we currently understand about plants, how to grow them and their uses. Today there are more than 2000 botanic gardens worldwide, devoted to the culture, study, and exhibition of documented collections of living plants.

But in the 21st century, botanic gardens are more than just beautiful places to visit. Climate change, habitat destruction, invasive alien species and over-exploitation all pose direct threats to plant survival and the earth’s biodiversity. Arguably the most important role of modern botanic gardens is the conservation of plants1. Indeed for some threatened plant species, botanic gardens have become the last hope for their precarious survival.

Ex situ and in situ conservation

Plants can be conserved both in their natural habitat and elsewhere.

  • Ex situ conservation aims to conserve and maintain samples of living organisms outside their natural habitat, in the form of whole plants, seeds, pollen, vegetative propagules, tissue or cell cultures.
  • In situ conservation (literally meaning ‘on site’), aims to conserve species diversity within normal and natural habitats and ecosystems, through habitat restoration and species recovery.

Botanic gardens support plant conservation in a variety of ways

Botanic gardens maintain living collections of plants ex situ, often displaying plant species under various groupings for show and conservation, to maintain a living store of genetic diversity that can support many activities in conservation and research.

Conservatory Royal Tasmanian Botanical Gardens Nov 2015

Fig. 2 Conservatory Royal Tasmanian Botanical Garden

Horticulture and cultivation allows botanic gardens to grow plants for show and pleasure but also an incredibly important place to house those that might become extinct in the wild (fig. 2). This maintains the conservation of genetic diversity ex situ but also allows plants to be used in restoration and rehabilitation of degraded habitats in situ.

Figure 3. Cultivation of the sub-antarctic megaherb Pleurophyllum hookeri (Asteraceae) in refrigerated units at the RTBG nursery

Fig 3. Cultivation of the sub-antarctic megaherb Pleurophyllum hookeri (Asteraceae) in refrigerated units at the RTBG nursery

Figure 3. Cultivation of the sub-antarctic megaherb Pleurophyllum hookeri (Asteraceae) in refrigerated units at the RTBG nursery. Pleurophyllum has proved difficult to establish and maintain in cultivation, but recent changes in horticultural practice by head propagator Lorraine Perrins has met with Fig. 2greater success.

Botanic gardens are presented with the opportunity to store the seeds or germplasm of plants for future use, research and propagation. This is another method of ex situ plant conservation known as seed banking. Seeds must be carefully collected and stored to ensure maximum genetic diversity is retained, and much research is required to determine the best way of storing different seeds.

Pleurophyllum hookeri

Pleurophyllum hookeri

Botanic gardens may carry out research and development into plant taxonomy and genetics, phytochemistry, useful plant properties, efficient seed banking methods, plant translocation and many more botanical areas that support plant use and conservation. Research into how plants withstand degraded and changing environments is especially important in light of increasing human activity and predicted climate change.

Education is a historic strength of botanic gardens, allowing them to communicate the importance of conserving plants to a diverse audience, while demonstrating how this might be achieved. The RTBG provides a number of education programs.

Linking plants with the well-being of people, and also helping conserve indigenous and local knowledge, encourages the sustainable use of plant resources for the benefit of all, as part of sustainable development.

References

NRMMC (Natural Resource Management Ministerial Council) (2004). National biodiversity and climate change action plan 2004-2007, Australian Government Department of Environment and Heritage, Canberra.