• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases
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Lathraea clandestina
Purple toothwort, Lathraea clandestina, grows in carpets of glossy, leafless flowers that appear in early spring. The plant is a parasite that has no photosynthetic parts and the richness of this display is afforded entirely from the resources of the host plant on which the toothwort feeds.

Lathraea clandestina colour forms
Though usually deep violet, the flowers of purple toothwort do occasionally occur in paler colour forms for which RHS Botanist James Armitage has provided the names L. clandestina f. rosea (pink) and L. clandestina f. albiflora (white).


Rafflesia arnoldii (photo by Stewart McPherson)
Like purple toothwort, the Sumatran native Rafflesia arnoldii is a parasitic plant which claims the distinction of having the largest flowers of any species on earth. Individual blooms can measure over a metre in diameter and have the colour and smell of putrefying flesh, features which make them irresistible to the flies that pollinate them. The dispersal of the resulting seeds is said to be affected by elephants. The genus name Rafflesia commemorates Sir Thomas Stamford Bingley Raffles, statesman and naturalist, the founder both of modern Singapore and the London Zoo.

Lathraea clandestina herbarium specimenEarly 20th century archive shot of Seven Acres

Left: herbarium specimen of L. clandestina: Specimens of Lathraea clandestina held in the RHS Herbarium collected in the early 1870s from a natural population growing in Indre, France. The collection notes report that the plant grew in moist woods and along river banks on Alnus and Populus. Right: at Wisley, purple toothwort was first recorded growing 'under the willow by the pond', a tree that can be seen in this picture of Seven Acres from the RHS Archive. Though the willow has long gone, Lathraea clandestina can still be found on the same spot where it has latched on to the roots of a dawn redwood (Metasequoia glyptostroboides) that grows there now.

E A Bowles with an RHS Committee at the Chelsea Flower Show in 1930 E A Bowles (front row, second from left) with an RHS Committee at the Chelsea Flower Show in 1930. Bowles was a prominent horticultural figure with a taste for the unusual who grew purple toothwort in his garden at Myddelton House, Enfield, perhaps originally as a plant received from cousins of his in Spain. He records using his position at the head of the table as Chairman of the RHS Scientific Committee to fire seeds from the explosive pods of Lathraea at fellow Committee members. Bowles devoted a portion of his garden known as the ‘Lunatic Asylum’ to the freaks and oddities of the plant world and a similarly strange range of plants can be found growing at Wisley in the area known as Bowles’s Corner.

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