About Berberis canadensis Mill.
Berberis canadensis Mill. is a deciduous shrub that can be hard to tell apart from the introduced, weedy Berberis vulgaris within its native range. Key distinguishing features for B. canadensis include brown, purple, or reddish second-year branches (instead of grey), fewer teeth along leaf edges, and fewer flowers per inflorescence. On average, this shrub reaches 1 meter (3 ft 3 in) in height, and may grow up to 2 meters (6 ft 7 in) tall. It spreads via rhizomes to form large clonal stands. Rhizomes allow the plant to absorb more nutrients from soil, letting it survive in relatively dry environments. Stems of B. canadensis are hairless, not extensively branched, dimorphic in growth, and range in color from green, purple, red, to brown. Leaves are arranged alternately, have 8 mm (5⁄16 in) petioles, are covered in a white waxy glaucose coating, are thin and smooth, and have an ovate shape. A seemingly random venation pattern is visible on the underside of leaves. Flowers grow in racemes that are typically 2–5 cm (1–2 in) long. Each flower has six cup-shaped, notched petals arranged in a double row, with one petal overlapping another. Flower color ranges from yellow to dull whitish yellow, with a bright green stigma protruding from the center. The stamen reacts to physical stimuli by bending toward the stigma when stimulated. B. canadensis produces small, oblong, bright red edible berries that have a high acid content, giving the fleshy fruit an appealing tart taste. This species is native to 13 U.S. states. Historically, its range spanned the Appalachian Mountains from southern Pennsylvania to northern Georgia and Alabama, with scattered populations reported as far west as Missouri. It is currently considered extirpated from Pennsylvania, Alabama, Maryland, and possibly Arkansas. It grows primarily on rocky slopes of hills and mountainsides. It was once much more widespread, but the United States government has gradually eradicated populations due to the species' connection to wheat rust. The species appears to have reached an environmental equilibrium, with no further range expansion currently occurring. Unlike most plants whose growth is limited by weather, B. canadensis is primarily limited by soil composition and habitat openness. It grows in a wide variety of open environments, including dry woodlands and exposed hillsides. It tolerates a range of soil types from basic to slightly acidic, as well as extremely shallow, well-drained soils that only receive occasional moisture from seasonal rainfall. B. canadensis is a perennial plant that grows alongside many other plant species in its native habitat. The edible fruit of B. canadensis is widely used by people, and is rich in vitamin C. Historically, it was an important source of nutrition for Indigenous peoples of the southeastern United States. The juicy red berries can be cooked to make jelly, and their juice is a popular refreshment. Berries can also be pounded into an oatmeal-like paste, and are sometimes used to make alcoholic beverages. For medicinal use, the Cherokee Native American people have used B. canadensis as a remedy for diarrhea: bark is soaked in water, and the infusion is drunk to reduce symptoms.
