The major Barberry species in North Carolina have many similarities, but their backgrounds are very different. One (American Barberry) is an important and rare native plant, with state protected status. The other three (European, Wintergreen and Japanese Barberry) are introduced species which have become broadly naturalized in large parts of North America. Field identification becomes important in protecting the American Barberry and controlling Japanese Barberry, which is invasive in some areas. European Barberry has already been the target of a large scale eradication program, which has dramatically reduced its numbers.
American Barberry – Berberis canadensis
In North Carolina, American Barberry is ranked as Imperiled, with a Special Concern- Vulnerable Status. Part of its rarity is due to its predilection for unusual circumneutral soils over diabase or limestone rock. But there are also other complicating factors involved. At the end of this article, there is a link to a thought-provoking blog by Rob Evans that addresses the factors that may (or may not) have led to American Barberry’s rarity.
Below is a typical appearance of a small American Barberry shrub.
American Barberry has trifurcated (3 parted) spines on the branches. Japanese Barberry has a single spine. While Wintergreen Barberry also has trifurcated spines, its spines are proportionally much larger. Below is a close up of the American Barberry spine.
American Barberry leaves (below) are ovate to elliptical and have 1 to 9 bristles on each leaf margin. Wintergreen Barberry leaves are tough and evergreen, and have many firm bristles on each leaf margin. Japanese Barberry leaves are entire (smooth margined). This is the single best way to tell the three species apart in the field.
European Barberry – Berberis vulgaris
European Barberry is a native European shrub that was introduced into cultivation in the United States, and became widely naturalized. When it was discovered to serve as a host for wheat rust, a successful eradication program was mounted that reduced its numbers dramatically. It is not pictured.
Wintergreen Barberry – Berberis julianae
Wintergreen Barberry originated in China, and was imported as an ornamental. It is much less invasive than European or Japanese Barberry, but local escapes near ornamental plantings are possible, and they are known to persist for many years.
There are a few known specimens at Falls Lake, including a huge specimen at an abandoned homesite at the B. W. Wells State Recreation Area. There are also two very large plants at a wild slope overlooking the Falls Lake Dam. They are very difficult to see in the tangles of vegetation except when they bloom, as illustrated by the telephoto shots below. The bloom is so profuse and bright that it can be seen from a great distance.
The spines of Wintergreen Barberry are trifurcate, and very long and prominent, as illustrated below.
Wintergreen Barberry’s narrow leaves are thick, glossy, and evergreen. The leaves are stiff and leathery, with firm prickles on the edges. Illustrated below are the top and bottom of a typical leaf.
Japanese Barberry – Berberis thunbergii
Japanese Barberry does not serve as a host for wheat rust. Since it has not been targeted by an eradication program, and is a popular cultivated shrub, it has been widely and densely planted. Like the European Barberry, it has become naturalized and can be very invasive, especially in New England. It is the barberry that is most likely to be encountered in the Piedmont of North Carolina.
In the Falls Lake and Kerr Lake areas, Japanese Barberry is sometimes seen in association with two close relatives: Leatherleaf Mahonia (Berberis bealei) and Nandina or Sacred Bamboo (Nandina domestica). Like Japanese Barberry, both are members of the Barberry family, the Berberidaceae, although Nandina is somewhat of an outlier as it lacks spines. They have three things in common, as well as their botanical family association, that explains their presence in our parks and forests . Their seeds are readily dispersed by birds, they can thrive in shade, and they are not eaten by White-tailed Deer.
Japanese Barberry has a single spine (below) in constrast to the trifurcated spines of American and Wintergreen Barberry.
The leaves of Japanese Barberry are spatulate to ovate, and the margins are entire. Leaves are illustrated below.
Some plants retain a single bristle at the tip of the leaf, on an otherwise smooth margin.
The photo below attempts to compare the leaves of three barberry species. Berberis julianae (Wintergreen Barberry) is on the left, Berberis canadensis (American Barberry) is in the center, and Berberis thunbergii (Japanese Barberry) is on the right.
For an excellent article by Rob Evans on the state’s wild barberries, and especially about the effects of wheat rust on barberry populations, follow this link:
For more about the abandoned homesite at the B. W. Wells S. R. A., follow this link:
Note: corrections to text and photos have been made to correct an identification error. Many thanks to Bryan for pointing this out. (See comments below)