Variation of flavonoid patterns in Hordeum spontaneum and H. agriocrithon

Employing thin‐layer chromatography, 279 collections of Hordeum spontaneum C. Koch and 10 collections of H. agriocrithon E. Åberg were investigated. The three flavonoid patterns described earlier in H. vulgare were also found in H. spontaneum in the following frequencies: A (50 %), B (32 %) and C (3 %). The S pattern, described previously as characteristic of H. spontaneum , was found in only 15 % of the collections. In spite of this, we believe that the S pattern is characteristic of wild H. spontaneum . We attribute the high frequencies of the A and B patterns to hybridization between H. vulgare and H. spontaneum . Morphologically, these hybrid collections were generally typical H. spontaneum , with two‐rowed spikes and a brittle rachis. However, they are regarded to be weedy forms. On disturbed sites, owing to ecological demands, but also by chance, H. spontaneum may have to incorporate different genes from H. vulgare —among them genes for the A, B and C patterns. Controlled crossing experiments between the three chemotypes of H. vulgare (A, B and C) and the original one in H. spontaneum (S) were performed and gave in the F 1 generation the dominance relationship S > B > C > A. Thus, the dominant S pattern, which is practically absent in cultivated barley, must represent the wild type. In the 10 collections of H. agriocrithon , only patterns A and B were found.