Hazels bred for nut-production; intermediate in features between the parents but perhaps no longer in cultivation.
In 1975, South Korea’s Rural Development Administration undertook a hazel breeding programme which selected promising plants of native Corylus heterophylla and C. sieboldiana, and bred these with fruiting hazels of European origin. As C. sieboldiana produces nuts which do not fall free from the husk when ripe, its genes have been very little used in the breeding of modern commercial hazels. Ten selections of C. sieboldiana were made during the Korean trials, but none of these are known to have produced promising hybrids with the European plants (Molnar 2011). However, the American C. cornuta, which is quite closely related to C. sieboldiana, has been successfully used in the breeding of new hazelnuts in the United States and Canada.