19 May 2009

Lousewort makes a comeback

At attractive pink-flowered plant of acid heaths and meadows has been rediscovered at two sites in Brede High Wood.

Lousewort, Pedicularis sylvatica, is a hemiparasite.  Although it has chlorophyll and can therefore photosynthesise some of its own food, it also takes nourishment from surrounding plants, mainly Agrostis grasses.  This helps it to compete, despite its lowly stature, on the low-nutrient soils it prefers. 

It is related to yellow rattle, Rhinanthus minor, another hemiparasite found usually in better, drier grasslands and lousewort also has seed pods that rattle when ripe.  By reducing the vigour of grasses, both plants help to provide opportunities for other plants and are therefore often regarded as being of particular conservation value.

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The name 'lousewort' is said to derive from a reputation in the past that if it was grazed by sheep they suffered from lice.  Sheep and cattle grazing on the kind of poor land where it grows would have been likely to be in poor condition and therefore more susceptible to lice.

I am not entirely convinced by this explanation as 'wort' plants so often seem to have been used in medicine and lousewort was once recommended to stop bleeding.

I last saw lousewort in Brede High Woods in 1997, but then only one plant, so it is particularly surprising that it has suddenly turned up in some quantity in two separate sites, both often visited.

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