Pedicularis palustris, commonly known as marsh lousewort,
Description
The nominate
subspecies Pedicularis palustris subsp.
palustris, which occurs in the west of the range, is a straggly
biennial plant with a much-branched, usually erect stem up to tall. The leaves are alternate or opposite, with a short stalk. The leaf blades are triangular-
lanceolate to linear, with pinnate lobes and toothed margins. The
inflorescence is a
raceme with leaf-like bracts. Each bilaterally symmetrical flower has a short stalk and a large, rounded, toothed
Sepal. The flower is reddish-purple and up to long, with five
fused into a tube, the upper lip being slightly shorter than the lower lip. The fruit is a capsule. The other subspecies,
Pedicularis palustris subsp.
karoi, which occurs in the east of the range, is an
annual plant and has smaller flowers.
This species can be distinguished from common lousewort (
Pedicularis sylvatica) by having two calyx lobes rather than four, and four small teeth at the tip of the upper lip rather than two. It is also taller and more erect, and is found in wetter locations.
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Distribution and habitat
Marsh lousewort is found in central and northern Europe and Asia. In Europe, it occurs in Scandinavia and southwards through most of Europe at altitudes of up to .[
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Ecology
Marsh lousewort is a semi-parasitic plant, the roots sucking nourishment from adjacent plants. The flowers are Pollination by and ; these land on the lower lip, which droops under their weight allowing them to thrust their head inside the flower and extract the nectar, getting powdered with pollen at the same time.
