The parasitic purple toothwort, Lathraea clandestina, is flowering now.
The Woodland Garden at Kew, around the Temple of Aeolus, is beginning to reach its spring best, with a range of bulbs and other woodland perennials flowering in the spring sunshine. One of the more unusual looking plants is a parasite known as purple toothwort, Lathraea clandestina. This species is totally dependent on the food produced by other plants to survive so it is called an 'obligate parasite'. It has parasitised the largest tree in the Woodland Garden, the black walnut, Juglans nigra, and the flowers sprout from the ground around the base of this mighty tree.
Purple toothwort (Lathraea clandestina) at the base of the black walnut
Lathraea clandestina is not native to the British Isles but was introduced in the second half of the nineteenth century and first came to Kew Gardens in 1888. It grows wild in Belgium, France, Spain and Italy but has become naturalised in Britain and even New Zealand. There is a British native species, L. squamaria, the common toothwort, but it is not as colourful as this species.
The flowers of purple toothwort (Lathraea clandestina) can appear some distance from the host tree
The easiest way to introduce L. clandestina to your garden is from seed scattered around or mixed in the soil, near a suitable host plant. It normally parasitises poplars and willows but has also been found on a number of other trees and shrubs including maples, yew, rhododendrons and alder. In early spring the flowers appear out of the ground. They are pinkish purple hoods that form dense clumps, sometimes a fair distance from the base of the tree on which they are living.
Flowers of purple toothwort (Lathraea clandestina)
Being a parasite, purple toothwort doesn't have any green leaves for photosynthesis, and after setting seed it disappears from view. It connects to the root system of its host, often deep down in the soil. Like many parasitic plants, feeding off another plant doesn't seem to have a detrimental effect on the host, and this strange species makes a fascinating addition to the woodland garden flora.
- Richard & Katie -