It seemed to me that if scions could be maintained in an approximately fresh state, they would furnish a key by which any variety of graft could be determined as easily as it could by its nuts.  I therefore set myself to preserve scionwood in its fresh state.  First, I cut five-inch pieces of plump, healthy wood, each piece having a terminal bud.  I placed these buds downward in large test tubes which I then filled with pure, strained honey.  Such models did very well for a time, but after about a year, the honey crystallized and of course the scions were no longer visible.  I emptied the tubes and washed them, cleaned the scions in warm water, replaced them and refilled the tubes with pure glycerine.  I submerged a thin, zinc tag, stencilled with the varietal name and bent to conform with the contour of the tube, inside of each one as a name plate which could not easily be lost or removed.  I also labeled each cork with the name of the variety enclosed so that any one of them could be located when looking down at a nest of tubes in a vertical position.

In order to display these preserved specimens at illustrated lectures, I had a rack made of redwood, of a size to hold twenty tubes.  The tubes could easily be taken from the rack for closer observation by members of an audience.  I find this to be an interesting adjunct to various nut culture exhibits I make in trying to promote nut culture education.

Since I was able to identify my unlabeled, hickory grafts by means of this catalogue of submerged scions, I consider it of great practical worth.  At the present time, I have about 50 hickory specimens, a good catalogue, although not a complete one.  I see no reason why the same thing could not be done with black walnut or any other kind of nut scions.

Chapter 20

HYBRIDIZING

Working with nature to develop new varieties of trees is fascinating although it requires infinite patience and study combined with skill and concentration.  A person without experience may taste of this pleasure, however, by trying his hand at cross-pollination, and there is no end to the number of hybrids possible.

In attempting to make crosses, one must necessarily understand the botanical relationship between the trees to be crossed.  Trees of the same species cross readily in almost all cases; trees of the same genus are not as easily crossed; trees belonging only to the same family are usually difficult to cross.  It is generally assumed that trees not in the same family are impossible to hybridize.  The plum serves as a practical example of this.  The American wild plum crosses readily with almost any other plum and particularly well with the Japanese plum.  These crosses have resulted in such phenomenal fruit as the Underwood plum, a cross made between species.  If a cross were made between a chestnut and a walnut, it would be between members of different families.  I recommend to anyone who is attempting to cross-pollinate for the first time, that he limit his work to crosses made within species.  His chances of success will be greater and such success added to the experience he is acquiring, will give him the background needed for more difficult hybridizing.