Stems: glabrous, leafy to the top. Leaves: all cauline, lanceolate, undivided, finely serrulate. Flowers: few, in short leafy racemes; calyx oblique, deeper cleft before than behind, the lobes abruptly acuminate; galea produced into an incurved beak, nearly as long as the broad lower lip, hamate-deflexed.

The dull white or very pale yellow beaked flowers of the White Lousewort are set in a close cluster at the top of the stalks, and are embedded amongst small deeply-fringed leaves.

The repellent common name of this plant is derived directly from the Latin one, which was bestowed upon it because once upon a time farmers believed that when their flocks fed upon these flowers the sheep were liable to be attacked by certain tiny lice, called pediculus.

Pedicularis contorta, or Contorted Lousewort, is very like the White Lousewort but has cream-coloured flowers set singly all the way up on the slender stalks. Its foliage is fern-like and often tinged with reddish-brown; long leaves grow out from the base, and small ones are interspersed with the numerous blossoms on the stems.

The Contorted Lousewort grows at very high altitudes, being usually found at 7000 feet.