Conopholis is a small genus of holoparasitic flowering plants in the family Orobanchaceae, order Lamiales, described by the German botanist Carl Friedrich Wallroth in 1825. The genus is native to North America and parts of Central America, and is commonly known as cancer-roots — a name that reflects the knotted, root-like appearance of the flowering shoots that emerge from the ground.
Members of Conopholis lack chlorophyll entirely and cannot photosynthesize. Instead, they parasitize the root systems of host trees — most commonly oaks (Quercus spp.) — from which they obtain all water and nutrients. The above-ground portion of the plant consists of a dense, fleshy, scaly spike covered in tightly overlapping bracts and small tubular flowers, giving the whole structure a superficial resemblance to a pine cone or a cob of corn. This corn-like appearance led to the folk name bear corn for Conopholis americana in the Blue Ridge Mountains of the eastern United States, where black bears are known to feed on the plant.
The genus currently contains two accepted species: Conopholis americana, the American cancer-root, which is widespread in eastern North America, and Conopholis alpina, the alpine cancer-root, which occurs in the mountains of Mexico and the southwestern United States (including southeastern Arizona). Conopholis alpina is further divided into varieties, including C. alpina var. mexicana, the Mexican cancer-root.
Etymology
The genus name Conopholis derives from the Greek words konos (cone) and pholis (scale), referring to the cone-like, scale-covered appearance of the flowering spike. The common name "cancer-root" alludes to the plant's parasitic attachment to host roots. In the Appalachian region C. americana is locally called "bear corn" because the stout scaly spike resembles an ear of corn.
Distribution
Conopholis americana is found across eastern North America, with a notable presence in the Blue Ridge Mountains. Conopholis alpina and its variety mexicana occur in the mountain ranges of Mexico and the southwestern United States, including southeastern Arizona.
Ecology
Conopholis species are obligate holoparasites, entirely dependent on host-plant roots — principally oaks (Quercus spp.) — for water, minerals, and carbohydrates. They produce no chlorophyll and carry out no photosynthesis. The fleshy above-ground spike emerges seasonally to flower and set seed; the rest of the plant's life cycle is conducted underground, attached to host roots. Conopholis americana is notably consumed by black bears, which feed on the nutrient-rich spikes in spring, earning the plant the folk name "bear corn" in parts of Appalachia.
Taxonomy Notes
Conopholis was established by C. F. Wallroth in 1825 (published in Orob. Diask. 78). It is placed in Orobanchaceae (the broomrape family), a family notable for including numerous parasitic and holoparasitic genera. GBIF recognises two accepted species with several infraspecific taxa, totalling six accepted taxa within the genus.
