Natural hybridization in western gooseberries (Ribes subgenus Grossularia: Grossulariaceae)

We describe three cases of hybridization between species of Ribes in the Klamath Mountains of northern California and southern Oregon. Based on their intermediacy and reduced pollen viability, we identified putative hybrids between R. lobbii and R. roezlii var. cruentum, R. binominatum and R. marshallii, and R. binominatum and R. lobbii. The hybrids live in recently cleared forests, where logging created extensive areas suitable for seedling establishment. Even though they are partially fertile, backcrossing and interbreeding have not generated an extensive array of recombinant types. Judging from field observations and surveys of herbarium specimens, hybridization between these species of Ribes appears to be uncommon, and there is little evidence that introgression is blurring the distinctions between them.