The Threatened Plants Project (TPP) is a ground-breaking venture to discover which garden plants are rare and which ones aren't, which are actually worthy of being conserved, and do something about it.
Background to the project
The history of British horticulture spans 400 years, 15 generations. Our cultural heritage of expertise is no less precious than the genetic conservation of particular plants, and cultivated plant varieties – cultivars – embody both.
Since 1987, nearly 85,000 cultivars in 1,000 genera have been commercially available, according to RHS Plant Finder data. Many are no longer, but no one knows which are most urgently in need of conservation, as very little research has been done.
Plant Heritage, the world's leading garden plant conservation charity, has been conserving cultivated plants for 30 years. Founded as the National Council for the Conservation of Plants and Gardens, its main activity has been the establishment and support of National Plant Collections®, of which there are now around 650. Rare plants have been sought for collection holders since 1981, through the Pink Sheet and other lists of desiderata.
Other organisations’ conservation schemes address specific groups of plants, but the Threatened Plants Project is the first systematic treatment of all genera grown in horticulture across England, Wales, Scotland, Ireland, the Isle of Man, Guernsey and Jersey.
The process
For every genus:
1. Volunteers help assess rarity of individual cultivars using RHS Plant Finder data (1987-present)
2. Living collections' plant records are checked
3. Experts are invited to comment on threatened cultivars’ merit, according to horticultural, utility, and heritage value; so that
4. The most worthy can be put forward for conservation