Foster's architecture finds a welcome in the valleys, reports Carolyn O'Grady.
The National Botanic Garden of Wales, set on an 18th-century estate once owned by property developer and financier William Paxton, is not just astonishing to look at, it's also breaking new ground in environmental sustainability.
The biomass furnace uses wood - a renewable energy source - to heat the great glasshouse and other buildings. A sewage treatment works uses micro-organisms to purify the waste of visitors, recycling it to feed the plants.
The 568-acre garden, which has been open since May, is mostly parkland but also has the world's largest single-span glasshouse. Designed by Norman Foster, this elliptical canopy covers 4,800 sq metres and tilts by seven degrees to allow in maximum sunlight. Computerised sensors monitor the temperature and humidity and adjust the 785 glass panes and activate fans to give a gentle breeze.
Although its shape is designed to blend into the undulating hills, it compellingly dominates the site and a group of 16 and 17-year-olds from Queen Elizabeth Cambria school, Carmarthen, was itching to see inside.
The Great Glasshouse is dedicated to plants which thrive in a Mediterranean climate, which is hot and dry in summer and cool, wet and windy in winter. Although this climate effects less than two per cent of the Earth's land, 20 per cent of plant species are found there and they are under-represented in other botanic gardens, explains education officer Chris Millican.
"Many of the habitats are endangered, due mainly to human activities, including urban development, agriculture, recreation and the introduction of invasive plant species.
"They are also educationally interesting, with lots of clear adaptations to habitat," she says.
Under the glass canopy, the terrain is divided into regions: parts of Europe, North and South Africa, the Canaries, Australia, California and Chile. A ravine with a waterfall breaks up the dry landscape and rocky terraces. In time, the effect will be of luxuriant growth. The sandstone terrain is already dramatic and the fire-blackened Australian grass trees (which are burnt by blowtorch) ofer a vivid contrast. Eventually there will be more than 10,000 plants and 1,000 species.
Fire, Ms Millican explains, is an important part of Mediterranean ecosystems, stopping stronger species from overshadowing more delicate ones and promoting flowers or the release of seeds.
She points out plants that camouflage themselves so as not to be eaten. Bulbous plants survive the dry summers by retreating underground until the rains begin.
Teacher Allan Carter says he is delighted by the visit to the garden, which has given him plenty of new ideas for geography and biology A-level project work.
But this place is not just for secondary schools. There is plenty to occupy younger visitors. There is, for instance, a nature trail to follow and an interactive exhibition called Plants in Action, which illustrates photosynthesis, pollination and the food chain and is designed for young children.
There are walks along the lakes which form a necklace around the estate. At a discovery centre, on stilts over the water, children can go pond-dipping and identify their finds under microscopes.
There is an exhibition on the physicians of Myddfai, celebrating Carmarthen's ancient tradition of plant medicines and the Wallace Garden is dedicated to an understanding of plant genetics. Among smaller features is an ice house, recently colonised by bats. There are plans to install a camera to watch them.
The garden is an awesome achievement. Designed and built at a cost of pound;43.3 million, it already gets more visitors than predicted. In its first two months, it received 85,000 visitors. By 2005, it is hoped there will be 250,000 a year.
The National Botanic Garden of Wales, Middleton Hall, Llanarthne, Carmarthenshire SA32 8HG. Tel: 01558 668768; fax: 01558 668933.
www.gardenofwales.org.uk Schools officer: Mari Thomas. Open daily except Christmas Day. September-October 10am-5.30pm; November-April 10am-4.30pm; April-August 10am-6pm. Admission: pound;2.50 per pupil, accompanying adults free.
Study programmes on plants, habitats and sustainable development, plants and health, and genetics. Teacher's notes and activity sheets for KS1 to A-level.