As if the education of children were not enough, some schools, set in great country houses, also bear the awesome responsibility of looking after a great historic garden.

Stowe School in Buckingham strove for many years to maintain a garden described as “the largest work of art in Britain”, containing almost as many temples as students, until the National Trust stepped in to help.

On a lesser scale, dozens of private and state-funded schools find themselves looking after such treasures as a good 18th-century landscape park, or a 19th-century walled garden and pleasure grounds. It is expensive work that requires much thoughtful and long-term planning if the garden is to thrive or even survive.

Some schools find themselves caring for important collections of trees. It is a responsibility that can be borne reluctantly in silence, or welcomed and developed with activities that can involve the students. Some schools now hold national collections of particular groups of plants, such as walnuts and cherries.

The system of national collections is co-ordinated and validated by the National Council for the Conservation of Plants and Gardens. The NCCPG was set up 20 years ago to conserve the wealth of plants in British gardens - wild species introduced from abroad as well as highly-bred cultivated varieties.

Some collections have come about because someone had a deep horticultural or scientific interest in, say, stonecrops or lungworts. Others because people have found themselves, as owners of a property, coincidentally owners of a fine collection of oaks or waterlilies.

Recognised collections still belong to the owners. But the NCCPG’s work is to co-ordinate those collections, making sure the collection holders have access to the means of accurate identification and recording, and offering contact with other specialists. Vitally, the NCCPG encourages collection holders to plan for the long term, making sure fine collections remain safe when an owner moves house or dies.

A good plant collection, whether of 19th-century peony varieties or modern hardy geraniums, is like a book of fine wallpapers. It has a place in the past and another in the future. As long as the collection survives, the plants can be propagated and used again.

Canford School, near Wimborne in Dorset, has a 260-acre deer park with many fine trees. It is home to the national collection of walnuts (the species in the genus Juglans, not the cultivars bred for fruit production). It is a small, manageable genus of almost a dozen trees and shrubs, and Canford has most of them, from Juglans ailantifolia, a tall Japanese species with leaves a yard long, to the bushier Californian Juglans microcarpa. The collection’s value to the school is principally as a botanical focus for its approach to the park. Andrew Powell, head of biology and master in charge of the arboretum, works with the students to map, measure and record all the planting in the park on computer, and periodically produces an updated guidebook to the more important trees.

Handcross Park School in West Sussex has a national collection of Japanese flowering cherries. The collection was set up by head of science Everard Daniel just before the great storm of 1987. Handcross was one of the areas worst hit by the storm, which wrought havoc throughout the 52-acre park. Nymans Garden, at the other end of the village, was flattened.

Since the storm, new planting of shelter belts, parkland trees and smaller ornamentals has taken place throughout the park. More than l00 flowering cherries have been planted in more than 80 different varieties.

The new trees are planted by the students, with each sponsored by a student and his or her family and marked with a plaque giving details of the tree and the name of its sponsor.

“We don’t use the collection formally for teaching purposes,” says Mr Daniel, “but we do keep a record of the trees’ growth, and the students are encouraged to recognise the importance of biodiversity. They take enormous personal pride in their own trees.”

NCCPG Courtyard, RHS Garden, Wisley, Surrey GU23 6QP.Tel: 01483 21146