XVI International Botanical Congess

The Corylus cornuta complex consists of one to four species, currently recognized as one N. Amer. species with two subspecies and one eastern Asian species with two varieties. Especially poorly understood is the relationship between western N. Amer. C. cornuta ssp. californica and northern/eastern N. Amer. C.c. ssp. cornuta. C.c. californica exhibits wide variability and is contiguous with C. c. cornuta where the two grade into each other, yet this latter hazelnut appears more similar overall to the eastern Asian C. sieboldiana. Principal components and cluster analyses based on 30 continuous and ordered multistate characters grouped Br. Columbian to eastern N. Amer. specimens closer to the eastern Asian than to the west coast state specimens. While future molecular analysis may help clarify relationships within the complex, this study supports separation of N. Amer. beaked hazelnuts into two species.