I found the first point of similarity with the filbert is in the involucre covering the nut.  In the wild hazel, this folds against itself to one side of the nut, while in the filbert it is about balanced and if not already exposing a large part of the end of the nut, is easily opened.  The involucre of the Winkler hazel is formed much more like that of the filbert than that of the hazel.  In Corylus Americana this involucre is usually thick, tough and watery, while in the filbert it is thinner and drier, so that while a person may be deceived in the size of a hazelnut still in its husk, he can easily tell that of a filbert.  This is also true of the Winkler whose involucre is fairly thick but outlines the form of the enclosed nut.  Another feature about the involucre of the Winkler which classes it with the filberts rather than the hazels is in its appearance and texture, which is smooth and velvety while that of the hazel is hairy and wrinkled.

The staminate blooms of the Winkler hazel show similarity to those of both filberts and hazels.  Sometimes they appear in formation at the ends of branches, much as those of the European filberts do, in overlapping groups of three or four.  Again, they may be found at regular intervals at the axis of leaf stems very much as in the case of the American hazel.  The buds on the Winkler hazel are dull red which is also true of those on the hybrid hazilberts, another indication of hybridity.

The initial growth of the embryo nut is very slow in the Winkler as it is in the filbert, as contrasted with the very rapid development of the native hazel embryo which matures in this latitude about one month ahead of the Winklers and some filberts.  Although Winkler nuts are shaped like hazels and have the typically thick shells of hazelnuts, their size is more that of a filbert usually three times as large as a native hazel.

During the years between 1942 and 1945 many new hybrids between filberts and hazels were produced.  Four wild varieties of hazels, which had unusual characteristics such as tremendous bearing and large size nuts and others having very early maturing or very thin shelled nuts were used as the female parents in making the crosses.  Pollen was obtained from other parts of the U. S. or from filbert bushes which were growing on the place.  Crosses included pollen of the Barcelona, Duchilly, Red Aveline, White Aveline, Purple Aveline, the Italian Red, Daviana and several hybrids between other filberts and hazels.  By 1945 the number of these plants were in the neighborhood of 2000 and by 1952 considerable knowledge had been gained as to the hardiness, blight resistance to the common hazel blight (known scientifically as cryptosporella anomala), freedom from the curculio of the hazelnuts (commonly known as the hazel weevil) and resistance to other insect pests.  Also, considerable data had been accumulated by cataloging over 650 trees each year for five years; cataloging included varied and