Berberis canadensis, commonly known as the American barberry or Allegheny barberry, is a member of the family Berberidaceae. Berberis canadensis is one of only two simple-leaved or 'true' Berberis indigenous to the United States. The other is B. fendleri of the southwest U.S. The epithet "canadensis" literally means "Canadian" but was often used by 18th-Century botanists to refer to any plants growing in northeastern North America. Morphology In its native range, B. canadensis can be difficult to distinguish from the introduced weed species B. vulgaris. Useful distinguishing traits are that the second-year branches are brown, purple, or reddish (rather than grey) and there are fewer teeth along the edge of a leaf, and fewer flowers in an inflorescence. Berberis vulgaris is a deciduous shrub, which grows, on average 1 meter in height, sometimes reaching as high as 2 meters. It spreads by rhizomes, forming large stands of clones. Rhizomes enable the plant to absorb more nutrients from the soil. This enables the species to grow in relatively dry environments. Stems of Berberis canadensis are hairless, not extensively branched, and range in color from green, purple, red, to brown. Stems also grow in a dimorphic fashion. The leaves on the shrub are arranged in an alternate pattern with petioles 8 mm in length and covered in a white waxy coating known as glaucose. In addition, leaves are thin and smooth and ovate in structure. A seemingly random venation pattern is visible on the underside of the leaves. Distribution Berberis canadensis is indigenous in 13 of the 50 states of the United States. Berberis canadensis occurs naturally from the Appalachian Mountains from southern Pennsylvania to northern Georgia and Alabama. Scattered populations have also been reported as far west as Missouri. The species primarily thrives on rocky slopes on the sides of hills and mountains. The species used to be a lot more prevalent in the past, however due to its connection with wheat rust, the United States government has slowly been eradicating the species. It seems that the species has reached an equilibrium with the environment, thus indicating no further expansion of the range. Unlike most plants whose growth is restricted by weather, B. canadensis is primarily restricted by soil composition and habitat openness. Habitat and ecology Berberis canadensis grows in many diverse open environments. It can be found in dry woodlands or on exposed hillside. The species grows in different soils