The Threatened Plants Programme helps National Collection holders, head gardeners and plant enthusiasts identify rare plants and prioritise their conservation efforts
“The wealth of information – and I’ve no other way to access it – is worth its weight in gold,” Dan Luscombe, Curator, Bedgebury National Pinetum and Forest
Camellias — a case study
Camellias have been a popular plant for UK gardens since their introduction in the 1700s. In that time, over 1,700 different varieties (cultivars) are known to have been grown in the UK or Ireland.
In 2020 we reviewed the National Plant Collections of Camellia for an article in the Rhododendron, Camellia and Magnolia Group's Journal about how these are contributing to the conservation of this genus in the UK. By comparing records from nurseries, National Collections, Plant Guardians and hundreds of historic and botanic gardens around the UK and Ireland we found that over 1,500 of these cultivars could still be found. However, half of these were assessed as Threatened, because they were no longer reliably available from commercial suppliers.
Camellia 'Dainty' Endangered cultivar, only known from one location
Jim Stephens
Camellia 'Mattie Cole' Vulnerable cultivar. Not available commercially but growing at six locations
Jim Stephens
National Collections
At the time, there were seven National Collections of Camellia, the majority held in Cornwall. We found that, between them, they held more than half the cultivars that could still be found. The largest collection, at Mount Edgcumbe, had 391 cultivars assessed as 'threatened'. To the best of our knowledge, 126 of these plants were not held anywhere else in the UK or Ireland. They used this information to prioritise plants for propagation.
At least 124 of the cultivars that we identified were only recorded in one or two locations, and not in a National Collection. Knowing that a plant is the last of its kind is useful for gardens managers. We could not find any official records for 177 cultivars, such as Camellia japonica 'Dianthiflora'. This was first recorded in the UK in 1822 and is surely out there somewhere? The list is here — could one be in your garden? Read the full article from the Rhododendron, Camellia and Magnolia Group's Journal.
Hardy garden chrysanthemums
Plant Heritage did a detailed review of hardy chrysanthemums in 2019. The majority (73%) were found to be safeguarded in a National Plant Collection and many cultivars featured in Plant Exchanges over the years. However, 21% were known at only one location, which prompted work to duplicate these. 22 cultivars were not found in any location - so categorised as 'Critical in cultivation'. Plant Heritage member Judy Barker has made a major contribution to safeguarding hardy chrysanthemums by setting up a dispersed National Collection held over three different sites. Judy has published a flower-filled book called Hardy Garden Chrysanthemums, recommending 140 different named varieties.
Chrysanthemum 'Constable' Endangered cultivar in the National Plant Collection of Judy Barker
Judy Barker
Chrysanthemum 'Spartan Linnet' Endangered in cultivation
C Dawson
Chrysanthemum 'Spartan Linnet'
Other suggested chrysanthemums of interest were those from particular breeders or listed in particular nursery catalogues. Cultivar names starting ‘Spartan…’ were bred by Woolmans.
Many of these are either no longer available commercially or have very limited availability. One such cultivar, 'Spartan Linnet' was found growing in the garden of a Plant Heritage member.
Chasing Helen
Chrysanthemum ‘Helen’ was grown by Home Meadows nursery in Woodbridge. When the nursery closed, some of the plants were rescued by Plant Heritage's Suffolk Group members, who brought them brought back to health and donated them to Wimpole Hall in Cambridgeshire. In 2014, the Suffolk Punch Trust wanted to bring together a National Collection of Suffolk garden plants. They looked for 'Helen' in the local area and thought it was lost. However, through Threatened Plants Programme research, one specimen was found growing in the grounds of Temple Newsam garden in Leeds.
Home Meadows catalogue, 2000
Picea pungens 'Compacta'
Benmore Botanic Garden
Conifers at the National Pinetum
In 2019, Bedgebury, the National Pinetum asked for a review of its Collections, particularly the heritage cultivars of Chamaecyparis, Cryptomeria, × Cuprocyparis, Picea, Taxus and Thuja.
Our report found that 550 cultivars of the above genera were identified as Threatened in cultivation all across the UK and Ireland. 91 of these were endangered conifers found only at Bedgebury. “The wealth of information – and I’ve no other way to access it – is worth its weight in gold,” says Dan Luscombe, Curator. “I can put a value on some cultivars because I know how rare they are. Plant Heritage is the only organisation that focuses on that. This report helps with my propagation and accession planning.”
Specialist societies
It has been a pleasure for Plant Heritage to work with many specialist societies. The Hardy Plant Society’s Pulmonaria Group for example was instrumental in rescuing Pulmonaria ‘Red Freckles’, found growing only at RHS Wisley in 2012. They gave it to 8 people and one nursery for bulking up. The Clematis Society was the first to publish the complete list of threatened plants we identified for their genus in 2014, and gathered locations from members. More details here. The Hardy Plant Society Hardy Geranium Group have been evaluating threatened Geranium cultivars.
If you would like to work with us, please get in touch. We love to receive interesting plant lists, and help track down missing plants.
Pulmonaria 'Red Freckles' at Wisley
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