Pedicularis racemosa / leafy lousewort

Adjectives: forest openings, hemiparasite, native

Also known as: parrot’s beak, sickle top, sickletop lousewort

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The leafy lousewort is pretty easy to identify, even when it is not in flower. The plants have numerous stems arising from a perennial woody base (caudex), usually with maroon leaves (when young) and unbranched maroon stems. There are commonly dozens of clumps in the same area. The leaves are narrow and tapering, and slightly toothed on the edges. As the leaves develop, chlorophyll is produced and they turn green.

The flowers are very showy but small. They are white or pink and borne in clusters/racemes – hence racemosa. Each flower is divided into a curved or coiled beak-like upper lip and a wide three-lobed lower lip. This seemingly odd shape is an adaptation to pollination by bumblebees. The flowers arise in the axils of the upper leaves.

As noted elsewhere, it was once thought either that louseworts gave lice to people and cattle, or, that they could cure people or cattle of lice. Both hypotheses were supported equally (i.e. not at all). Nonetheless, leafy lousewort has a couple other weird tricks up its xylem. For example, in the complicated life cycle of the parasitic fungus that causes blister rust on some pines, one part of the cycle is spent on a non-pine, an “alternate host”. Leafy lousewort is one such plant. And as another… the leafy lousewort and other members of the genus Pedicularis are hemiparasites, i.e. green, but also parasitic.

In defense of most of the members of the Orobanchaceae, however, the actual known parasitic associations seem to be pretty few. Nevertheless, in the case of P. racemosa, I am willing to believe that a main parasitic phase occurs while the leaves are maroon.

At some point, someone who actually knows will set me straight.