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The article reports that Berberis thunbergii L. (Japanese barberry) holds significant market share in the commercial ornamental horticulture industry. Japanese barberry is grown by production nurseries and used in landscaping across the northern half of the U.S. It mentions that Japanese barberry's popularity as a commercial horticulture staple crop has also resulted from its ease of culture under production nursery conditions.

Berberis Xottawensis is the hybrid of B. vulgaris (common barberry) and B. thunbergii (Japanese barberry). In the wild, this interspecific taxon appears to have been largely overlooked. Here, we report that this hybrid is relatively widespread in Connecticut and Massachusetts. Furthermore, we present evidence that the hybrid individuals are capable of producing some viable seed and pollen. [ABSTRACT FROM AUTHOR]

Japanese barberry (Berberis thunbergii DC.) is a popular ornamental shrub used in garden and urban landscaping. Currently there are over 60 B. thunbergii cultivars in the market. To better distinguish its cultivars, we used the amplified fragment length polymorphism (AFLP) technique to develop DNA marker profiles for 59 cultivars and hybrids. These markers were used to authenticate the trueness-to-name of B. thunbergii cultivars in production and in the market, control for intracultivar genetic variants, and develop a molecular key to identify cultivars approved for importation in Canada. Polymorphic markers from seven primer combinations were able to clearly differentiate 57 of 59 cultivars evaluated. Two cultivars, Aurea and Aurea Nana, could not be differentiated because they had identical marker profiles. Among the 274 plants tested, 263 were confirmed to be true-to-name and correctly labeled, whereas 11 plants could not be confirmed true-to-name. Seven of the 20 cultivars evaluated exhibited detectable intracultivar genetic variation. 'Crimson Pygmy' had the highest number of plants exhibiting genetic variability. Overall, nursery producers and retailers do not appear to be mixing or mislabeling cultivars. A molecular key developed from a subset of 25 markers was able to accurately identify and differentiate the 11 B. thunbergii cultivars approved for importation in Canada. This key could be used in a cultivar verification program to facilitate international trade of B. thunbergii cultivars where wheat rust is a concern. [ABSTRACT FROM AUTHOR]

We investigated the role of an ornamental, purple-leaved specimen of Japanese barberry in a local invasion using parentage analysis. We focused on a landscape plant of B. thunbergii var. atropurpurea in Willington, CT, that was first established at least 30 years ago. We genotyped every barberry plant found within a 92-m radius of this individual, in contrast to feral populations that are distant from residential or commercial plantings, 14% of the 43 feral plants in our sample had purple foliage and 30% were found growing within 16.5 m of the focal individual. Parentage analysis identified seven plants (five purple-leaved and two green-leaved) as descendants of the focal individual. Five of these descendants are likely first-generation offspring and two are likely second-generation seedlings, in addition, one plant was identified as a backcross between the focal plant and one of its offspring. Our results show that purple-leaved Japanese barberry used in residential landscapes can contribute to plant invasions, at least under some circumstances. [ABSTRACT FROM AUTHOR]

Abstract: Japanese barberry (Berberis thunbergii DC) is an invasive shrub, widely naturalized across the United States, whose numerous cultivars remain an important horticultural commodity. Maintaining this crop for the future necessitates the development of sterile clones. Exposure to the mitotic inhibitors colchicine and oryzalin is a traditional method for inducing tetraploidy in breeding lines as a precursor to creating sterile genotypes. Treatments utilized pre-germinated B. t. var. atropurpurea seeds with emerged radicles. Seeds were immersed in aqueous solutions of colchicine (.02%, .05%, .1% and .2%) and oryzalin (.002%, .005%, .01% and .02%) dissolved in 1% DMSO for 6, 12 and 24h durations. Seedling ploidy level was determined via flow cytometry following 6 and 52 weeks of growth in the greenhouse. Both anti-mitotic chemicals proved effective at inducing tetraploidy and produced comparable efficiency rates. The survival rate of treated seeds decreased in response to both increased mitotic inhibitor concentration and longer exposure duration. While exposure to oryzalin produced greater seed mortality than colchicine, most seedlings that survived had altered ploidy levels. The most efficient oryzalin concentration was 0.002% with a rating of 28%, while the most efficient colchicine concentrations were in the range from 0.05% to 0.2%. Duration of exposure to mitotic inhibitor was not a significant factor over the range from 6 to 24h. Reversion of tetraploid plants to the diploid state occurred at a low frequency following a dormancy period. Some tetraploid seedlings derived from exposure to both chemicals displayed foliar abnormalities including irregular leaf margins and mottled lamina. The primary advantage of colchicine was low seedling toxicity, while oryzalin was notable for its ability to induce tetraploidy at low concentrations. [Copyright &y& Elsevier]

Cultivars of Berberis thunbergii DC. are among the most popular garden shrubs in the United States. Using 174 amplified fragment length polymorphism (AFLP) markers we were able to differentiate between 43 B. thunbergii cultivars and analyse the genetic similarity of 62 B. thunbergii genotypes, B. julianae, B. koreana, B. vulgaris and B. vulgaris 'Atropurpurea'. Seven different accessions of B. thunbergii 'Crimson Pygmy' from a variety of sources had identical AFLP profiles, indicating that there is only one genotype in cultivation and not a collection of similar genotypes. B. thunbergii cultivars 'Crimson Pygmy', 'Crimson Dwarf', and 'Monomb' Cherry Bomb™ could not be distinguished and appeared to be the same genotype. The B. thunbergii cultivars 'Concorde' and 'Criruzam' Crimson Ruby™ are most likely genotypes of B. × ottawensis since they formed a cluster with known B. × ottawensis cultivars. The B. thunbergii var. atropurpurea accessions analysed had Jaccard's coefficients ranging from 0.89 - 0.99 and, therefore, were probably derived from highly inbred seed. A dichotomous identification key was developed for 42 B. thunbergii cultivars and hybrids and B. vulgaris 'Atropurpurea' using 23 markers. This key can be used to ensure that only legal cultivars are sold, if cultivar-specific bans are enacted, and to prevent the importation of rust-susceptible cultivars into Canada. [ABSTRACT FROM AUTHOR]

While japanese barberry (Berberis thunbergii DC.) is an acknowledged invasive plant naturalized throughout the eastern and northern U.S., the danger posed by its popular horticultural forms is unknown and controversial. This work analyzed the reproductive potential and seedling growth of four ornamental genotypes Important to the nursery industry. Fruit and seed production was quantified In 2001, 2002, and 2003 for multiple landscape plants of B.t. var. atropurpurea, 'Aurea', 'Crimson Pygmy', and 'Rose Glow'. The overage number of seeds produced per landscape specimen ranged from lows of 75 and 90 for 'Aurea' and 'Crimson Pygmy' to 2968 for var. atropurpurea and 762 for 'Rose Glow'. Seed production relative to canopy surface area for 'Rose Glow' was similar to 'Aurea' and 'Crimson Pygmy' and all three cultivars were less prolific than var. atropurpurea in this regard. Cleaned and stratified seeds from var. atropurpurea, 'Crimson Pygmy' and 'Rose Glow' showed an average greenhouse germination rate of 70% to 75%, while 'Aurea' yielded 46% germination. A subpopulation of seedlings from each genotype accession was grown further outdoors in containers for a fag season to ascertain seedling vigor and development. The vigor of 1-year-old seedlings, as measured by dry weight of canopy growth, for progeny derived from 'Aurea' (0.70 g) and 'Crimson Pygmy' (0.93 g) was significantly less than var. atropurpurea (1.20 g) and 'Rose Glow' (1.33 g), These results demonstrate that popular japanese barberry cultivars express disparate reproductive potential that, after further study, may be correlated with invasive potential. Some popular commercial cultivars may pose significantly less ecological risk than others. [ABSTRACT FROM AUTHOR]