although the grafting itself was successful I found it tiresome to
prune, repeatedly, the suckers which constantly spring up during the
growing period and which are detrimental to grafts. Although they lived
for five years, these grafts suffered a great deal of winter-injury and
they never bore nuts. The one which lived for the longest time became
quite large and overgrew the stock of the wild hazel. This same plant
produced both staminate and pistillate blossoms very abundantly for
several seasons but it did not set any nuts in spite of the many wild
hazels growing nearby which gave it access to pollen. It is now known
that this hybrid is self-sterile and must have pollinators of the right
variety in order to bear.

My next work with members of the genus Corylus was discouraging. In
April 1929, I bought one hundred hazel and filbert plants from Conrad
Vollertsen of Rochester, New York, which included specimens of the Rush
hazel and of the following varieties of filberts:

Italian Red
Merribrook
Kentish Cob
Early Globe
Zellernuts
White Lambert
Althaldensleben
Medium Long
Bony Bush
Large Globe
Minnas Zeller
Marveille de Bollwyller