Excerpts from Jim Conrad's
Naturalist Newsletter

from the May 15, 2005 Newsletter issued from the Sierra Nevada foothills somewhat east of Placerville, California, USA
BROOM-RAPE/CANCER ROOT

broom-rape or cancer-root, OROBANCHUS FASCICULATAThe most interesting, exotic looking and strangely beautiful wildflower blooming right now appears in small clumps in pine straw along my jogging road. The plant is known by two undeservedly unfortunate names -- broom-rape and cancer-root. It's OROBANCHUS FASCICULATA of the Broom-rape Family, the Orobanchaceae. That's some at the right.

As typically is the case, what's visible in the above picture is just brownish-yellow, curve-tube flowers on stiff, slender pedicels. The plant's finger-thick, cream-colored stem lies completely buried within the pine straw. A point not to be overlooked is that this flowering plant possesses no green leaves or stem. It is completely lacking in chlorophyll, and thus is incapable of manufacturing its own food through the process of photosynthesis.

This is no problem for broom-rape, however, because broom-rapes are parasites stealing food from other plants. Broom-rape's simple roots grow through the soil until they encounter the root of a potential host species. Then the tip of the broomrape's root swells and surrounds the host's root. This swelling accounts for the "cancer" part of one of its names. The growth then produces filaments penetrating the host root, tapping into both the water-and-mineral conducting tissue (the xylem) and the tissue carrying the host's photosynthesized carbohydrates (the phloem).

That name broom-rape derives from completely innocent Latin origins. The Medieval Latin name was "rapum genistae," "rapum" being the term for "underground stock of a tree," and genistae being the genitive form of the word genista, which was the term applied to broom bushes such as the Scotch Broom I spoke of last week. Our plant was considered to grow on the roots of broom bushes.