ADVERTISEMENT. 
vi 
far as they point out to the cultivator the vegetable relatives, between which there 
is always the greatest probability of success in attempting the union, either by 
engrafting or inarching, or mixing the breed. At least, such natural groups 
generally indicate the confines, out of which species cannot be united by any of 
those means. All plants contained in the various periodical publications where 
the vegetables cultivated amongst us are treated of, have been most carefully 
enumerated up to the present moment; and this Compilation may be so far 
considered as a general index to them* 
