NAMING AMERICAN HYBRID OAKS. 



By WILLIAM TRELEASE. 



Plates I-III. 



(Read April 13, 19 17.) 



Two methods of designating hybrids are sanctioned by the In- 

 ternational Botanical Congresses of Vienna and Brussels — employ- 

 ment of a compound trivial name composed of the names of the two 

 parent species, separated by the conventional X sign, or use of a 

 new trivial name in a binomial preceded by the same conventional 

 symljol. Taking a now well-known oak hybrid as illustration, the 

 first method would cause it to be referred to as either Quercus alba 

 X Priiuis or 0. Primis X alba, and the second as X (?■ SauUi. 



Various qualifications of the first procedure have been proposed 

 or put in practice now and then to show which is the male and which 

 is the female parent species, or to indicate by use of the symbol > 

 or < which parent is more closely resembled by the hybrid. The 

 first of these is possible only when hybridization has been efi^ected 

 artificially or when the mother plant is known, so that uniformity 

 in its use and therefore general comparability is impossible. As a 

 fact no eft'ort has been made to indicate the resemblance to either 

 parent in the majority of cases ; nor is it likely that different ob- 

 servers would reach identical conclusions in this respect for many 

 specimens of hybrids because, among other things, no agreement 

 exists as to which of several non-concordant characters is to form 

 the basis of judgment. Amplification of this composite name 

 method permits the similar designation of secondary and tertiary or 

 higher hy1)rids, Init in an increasingly cumbersome way, so that the 

 polynomial indication of such forms becomes very quickly a con- 

 fused symbolically abbreviated description rather than a name. 

 Even in the simple case of such a first cross as has been taken for 

 illustration, every rectification of error in the names applied to 



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