Secondary chemistry of hybrid and parental willows: Phenolic glycosides and condensed tannins inSalix sericea,S. eriocephala,and their hybrids

Salix sericea andS. eriocephala differ markedly in secondary chemistry.S. sericea produces phenolic glycosides, salicortin and 2-cinnamoylsalicortin, and low concentrations of condensed tannin. In contrast,S. eriocephala produces no phenolic glycosides, but high concentrations of condensed tannins. Hybrid chemistry is intermediate for both types of chemicals, suggesting predominantly additive inheritance of these two defensive chemical systems from the parental species. However, there is extensive variation among hybrids. This variation may be due to genetic variation among parental genotypes, which genes were passed on, or to subsequent back-crossing. The differences in chemistry are likely to exert a strong effect on the relative susceptibility of hybrid and parental willows to herbivores.