Louseworts

Lousewort is the common name for plants of the genus Pedicularis. They are members of the Scropulariaceae or snapdragon family. There are about 500 species found world-wide. The further south louseworts grow, the more likely they are to grow at high altitudes. This makes Rocky Mountain National Park, with an altitudinal range from 7,624 to over 14,000 feet an ideal location to find louseworts. The park hosts seven of the nine species of louseworts that are found in the state of Colorado.

Louseworts are thought to derive their name from an old folk legend that livestock eating or grazing near the plants would develop lice. No evidence has been found to support this contention, however they are partially parasitic on other plants. Louseworts appear to be able to parasitize a very wide variety of plants, as no host specificity is known for any species. Wood betony (Pedicularis canadensis) is one of the two species of louseworts found in Colorado, but not reported from the park (the other being dwarf lousewort or P. centranthera). Wood betony has been used by Native Americans as a source of food and medicine to treat a wide variety of ills. Interestingly, a strong decoction of wood betony can be used to rid people and animals of lice, a possible alternative source of the name lousewort (i.e. louse = singular of lice and wort = an herb that treats) for this genus.

The park's louseworts include alpine lousewort (P. suedica spp. scopulorum per the USDA Plants database), bracted lousewort (P. bracteosa), giant lousewort (P. procera), little pink elephants (P. goenlandica), Parry's lousewort (P. parryi), purple lousewort (P. crenulata), and sickletop or rams-horn lousewort (P. racemosa). Key characteristics separating these species include the color of the flowers and whether the leaves are undivided (often long and tongue-shaped) or divided into lobes looking somewhat "fern-like" to most observers. So the next time you see a flower that looks somewhat like a snapdragon in Rocky Mountain National Park, take out your field guide and try to identify it. It might be one of the many lovely louseworts that make a home in the park.

Last updated: March 31, 2012

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