This is the first time that a definitive record of threatened cultivars has been established, which has found that more than two-thirds of cultivars are rare enough to be deemed threatened.
The charity, launched its Threatened Plants Project in 2009, but there has been no record for cultivated plants until now.
Plant Heritage conservation officer Mercy Morris said that it will not be possible to conserve all the plants listed but the charity would now be able to establish which plants should be saved, and conservation plans put in place: "Not only will we be able to highlight to head gardeners and estate managers which plants they hold are valuable and need conserving, but will also indicate where new National Plant Collections are needed, and what plants we can put into our Plant Guardian scheme."
Plant Heritage has compiled the information using plant records held by 819 public gardens including National Plant Collections, RHS Gardens, National and University Botanic Gardens, National Trust, The National Trust for Scotland, The National Trust for Northern Ireland, English Heritage, the National Arboreta, the Eden Project, County Councils and its own Plant Guardian Scheme.
Johnsons Seeds sponsors the Threatened Plants Project.
The list of threatened cultivars can be found on the Plant Heritage website at: http://www.nccpg.com/tpp/Technical-data.aspx