Whilst marsh lousewort (Pedicularis palustris) has much in common with its relative, the common lousewort, it also has some distinct differences and so should be quite distinguishable if found. It is generally found far less frequently that the common lousewort.
Marsh lousewort grows somewhat taller than its cousin, even growing to two feet tall in exceptional circumstances and is an erect plant whereas common lousewort is low growing and sprawling. The flowers of marsh lousewort are a much deeper colour, more red than pink and that redness gives rise to its other name, red rattle. Finally, the marsh lousewort likes much wetter conditions that the dampness favoured by common lousewort. Flowering from May right through until September look for marsh lousewort in marshes and fens. It has less of a preference for the acidic conditions favoured by common lousewort which also helps to separate them.
Like common lousewort it is a semi-parasitic plant, using various grasses as its host for nutrition, as well as fending for itself.Marsh Lousewort: the red rattle