FASHIONS change in the world of gardening as they do elsewhere.

Loss of habitat, environmental change, disease and simple changes in taste are threats to plant diversity.

In the first study of its kind, researchers at Royal Botanic Gardens, Kew found that 571 plant species have disappeared from the wild in the past 250 years.

UK-wide conservation charity Plant Heritage, formerly known as the National Council For The Conservation Of Plants And Gardens, says we cannot afford to be complacent about cultivated plants either.

Through its National Plant Collection scheme, individuals and organisations can pledge to preserve a collection of a related group of plants for the future.

From owners of historic estates to humble allotments, there are around 630 holders of National Plant Collections or “living libraries” as Plant Heritage calls them. There’s a guide for interested growers at www.nccpg.com

Glendoick
Glencarse, Perthshire

This year marks a century since plant hunter Euan Cox returned from Burma with the first rhododendron seeds to be grown and planted in the gardens at Glendoick.

With findings from expeditions to China and the Himalayas by three generations of the Cox family, the garden is home to several National Collections, including rhododendrons and azalea species and hybrids introduced from the wild or were bred by the family. Some are on sale at the garden centre.

3 Balfour Cottages
Menmuir, Angus

Home to the National Collection of vividly-coloured, velvety-flowered alpine auriculas, Alison Goldie and Mark Hutson’s small cottage garden at Menmuir, around four miles from Brechin, is full of more unusual plants such as fritillaria and trillium.

From potted herbs to a “jungle” of bamboos and a large display of bonsai and auriculas, there’s much here to interest a modern plant hunter.

Benmore Botanic Garden
Benmore, Dunoon

The entrance to the garden at Benmore is a spectacular avenue of 150 foot-high giant redwoods.

It’s a fittingly majestic introduction to the treasures within the 120-acre garden, which has National Collections of firs, spruce and South American temperate conifers. Visit the Bhutanese and Chilean pavilions, and take a walk to the restored Victorian Fernery with views looking out across the Holy Loch.

Logan Botanic Garden
Port Logan, Wigtownshire

Warmed by the Gulf Stream, Logan’s milder climate allows treasures rarely seen elsewhere to thrive, including plants from Australia, New Zealand, Southern Africa and South and Central America.

Known as “Scotland’s most exotic garden”, it holds National Collections of Leptospermum, Griselina, Cianthus and Gunnera, giant, rhubarb-like plants which can grow to around eight feet.

Dawyck Botanic Garden
Stobo, Peeblesshire

Dawyck is home to a rare trees and shrubs and the National Plant Collection of Larix and Tsuga.

With over 300 years of tree planting, its oldest tree is a silver fir (Abies alba), which dates from 1690. Other heritage trees include European larch (Larix decidua), thought to have been planted in 1725 in the presence of Carl Linnaeus, the Swiss botanist who pioneered taxonomy.

The garden is known for the distinctively upright, tall Dawyck Beech (Fagus sylvatica), discovered in 1860 by former estate owner Sir John Naesmyth.

The original tree still grows in the grounds of Dawyck House. Though the house is closed to the public, specimens propagated from the tree can be seen elsewhere around the garden.