Conopholis americana, American cancer-root or squawroot or bear corn, is a perennial, non-photosynthesizing (or "achlorophyllous") parasitic plant, from the family Orobanchaceae and more recently from the genus Conopholis but also listed as Orobanche, native but not endemic to North America and when blooming, resembles a pine cone or cob of corn growing from the roots of mostly oak and beech trees.
Conopholis americana is parasitic on the roots of woody plants, especially oaks (genus Quercus) and beech (genus Fagus). The only part of the plant generally seen is the cone-shaped inflorescence, which appears above ground in spring. The entire structure is a yellowish color, turning to brown and achieves heights of 10 centimeters (4 in) to 20 centimeters (8 in) tall.
Stout and unbranched 1.3 centimeters (0.5 in) to 2.5 centimeters (1 in) thick stems. Since C. americana does not photosynthesize it also does not have true leaves; it has instead simple, ovate, tiny scales 1.3 centimeters (0.5 in) long and brown, which appear underneath each flower.
Conopholis americana produces spikes of yellow to cream flowers densely crowded all around the stem. Each flower is 5-parted, 8 millimeters (0.3 in) to 13 millimeters (0.5 in) long, tubular with a swollen base and facing downwards. As the flowering spike matures and begins to wither and becomes brown throughout the summer and often persisting through the winter, by which time it has become shriveled and black. There is no noticeable floral scent.
Each flower is replaced by a seed capsule that is longer than it is wide and contains many small seeds. This plant spreads to new locations by reseeding itself.
The root system is parasitic on the roots of Oak trees (Quercus spp.); dependent on the host tree for its nourishment, the suckers of the parasitic roots cause the formation of large rounded knobs on the roots of the host tree.
Found growing on roots in wooded ravines in every state of the United States east of the Mississippi River.
It is considered an exploitably vulnerable species in New York, a threatened species in New Hampshire and a special concern in Rhode Island.