Purple-leaved Japanese Barberry (var. atropurpurea) Genotypes Become Visually Indistinguishable from Greenleaved Genotypes (Berberis thunbergii DC.) at Low Light Levels

Abstract

Abstract Japanese barberry (Berberis thunbergii DC.) is a popular nursery plant that has escaped from cultivation to establish invasive populations across the United States. Previous studies demonstrate that green-leaved feral plants adapt successfully to low light levels. The leaf color phenotype of purple-leaved Japanese barberry (Berberis thunbergii var. atropurpurea) seedlings grown under shaded conditions was studied to determine their appearance under low light conditions typical of wooded areas often invaded by barberry. Seedlings from B. thunbergii var. atropurpurea were grown in full sunlight and under three shade treatments (36, 50 and 72%). Seedlings were also grown in full sunlight and under two higher shade treatments (85 and 95%) in a second study. The hue angle of purple seedlings increased from a mean of 22.3 in full sun to 86.9 at 72% shade, reflecting a color change from violet-purple to green-umber. Foliage color also became more vivid and lighter as shading increased. All purple genotype seedlings appeared green when grown at 95% shade due to lack of anthocyanin production at this light exposure. Escaped barberry seedlings originating from landscape plants of var. atropurpurea may not be recognized as purple-leaved forms when they invade densely shaded woodland environments.