Marsh lousewort (Pedicularis palustris)

Marsh lousewort in flower
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Marsh lousewort fact file

Marsh lousewort description

GenusPedicularis (1)

Marsh lousewort or red-rattle is a widespread hemiparasitic herb (3). The stems and leaves are smooth, or have a few sparse hairs. The stem branches close to the base, and bears roughly triangular-shaped leaves with toothed lobes. The flowers are reddish-pink and the upper lip has a small tooth on each side (2). The name ‘red-rattle’ refers to both the colour of the flowers and the seed pods, which rattle when the seeds inside become ripe (4).

Also known as
Leaf length: 2 – 4 cm (2)
Flower diameter: 2 – 2.5 cm (2)
Height: 8 – 60 cm (2)

Marsh lousewort biology

Although it does contain the green pigment chlorophyll and photosynthesizes, marsh lousewort also obtains some nutrients by feeding on the roots of a host plant (3). It is therefore dubbed a ‘hemiparasite(3). It grows as either an annual or a biennial(3). The flowers are pollinated by various bumble-bees, which are attracted to the flowers by the nectar (2).


Marsh lousewort range

This plant is fairly common in much of Britain, and it has a wide distribution, reaching altitudes of up to 855 metres (2) . It has undergone a substantial decline in central and southern England (3). Elsewhere it is found in mainland Europe as far south as the Pyrenees. It also occurs in the Caucasus region (Georgia, Armenia and Azerbaijan) (2).

You can view distribution information for this species at the National Biodiversity Network Atlas.

Marsh lousewort habitat

As the name marsh lousewort suggests, this species is found in a broad variety of moist habitats such as wet heaths, wet meadows, fens, ditches, and valley bogs (3).


Marsh lousewort status

Not threatened at present, but has undergone as substantial decline (3).


Marsh lousewort threats

The decline of this species in central and southern England is due largely to the widespread agricultural improvement and drainage of the wet habitats in which it grows (3).


Marsh lousewort conservation

So far, conservation action has not been targeted at marsh lousewort, which is still fairly common in many parts of the country (2).

There may be further information about this species available via the National Biodiversity Network Atlas.

Find out more

For more on British native plants and for details of how to get involved in plant conservation visit the website of Plantlife, the wild plant charity:



This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:


Lives or grows for just one year.
A plant that lives for two years and typically flowers only in the second year.
A group of green pigments found in photosynthetic organisms (photosynthesis is a metabolic process characteristic of plants in which carbon dioxide is reduced, using energy absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product).
Plant that obtains some nutrition from a host plant, but is able to survive independently as it possesses the pigment chlorophyll and a root system.
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.


  1. National Biodiversity Network Species Dictionary (September 2003):
  2. Clapham, A.R., Tutin, T.G., and Moore, D.M. (1987) Flora of the British Isles 3rd Edition. Cambridge University Press, Cambridge.
  3. Preston, C.D., Pearman, D.A. and Dines, T.D. (2002) New Atlas of the British and Irish Flora. Oxford University Press, Oxford.
  4. Mabey, R. (1996) Flora Britannica. Sinclair-Stevenson, London.

Image credit

Marsh lousewort in flower  
Marsh lousewort in flower

© Gordon Maclean /

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