Definition of "mazzard"

In California three rootstock species are in general use. From fairly reliable estimates, about 65 per cent of the cherries grown in the state are grafted on mazzard (Prunus avium); 30 per cent are on mahaleb (P. mahaleb); and 5 per cent on morello (P. cerasus).

1951, Leonard H. Day, Cherry rootstocks in California, Berkeley, Calif.: College of Agriculture, University of California, page 4