TRELEASE— NAMING AMERICAN HYBRID OAKS. 47 



matter of fact, the name was given to a definite plant form, and 

 follows that form whatever changes of theory or knowledge its 

 parentage may undergo. For this reason, X Q- Hollickii passes 

 into synonymy as a mere equivalent of the earlier name X Q- 

 hetcrophylla; and the latter does not in any way affect the naming, 

 on its own merits, of a hybrid between Phcllos and vchttina when- 

 ever that is brought to light. Such a plant is believed to be that 

 which is here called X Q- diihia, though some doubt attaches to its 

 parentage. If an error has been made, X Q- dubia in its turn will 

 still stand for this form if it can be identified, which is less certain 

 than for heterophylla; and a real hybrid between Phellos and 

 velutina, if ever found, will finally be given a definite name quite 

 irrespective of these eft'orts. A somewhat comparable case is 

 aft"orded by X Q- ritncinata. 



In my study of the American oaks, briefly summarized recently ,- 

 I have had to account for a considerable number of hybrids, some 

 of which have been described or even figured, occasionally as species 

 in the ordinary use of the term, and some of which have been made 

 known by reference to specimens more or less generally distributed 

 by their collectors. No collective treatment of these forms has ever 

 been made : they are not to be found severally assembled in any 

 herbarium that I have seen, being inserted sometimes under one 

 parent, sometimes under the other — now^ under one name, now 

 under another for the parental species — and exceptionally under 

 binomials of their own. The following table accounts for every- 

 thing of this description that I have encountered either in herbaria 

 or in publications on Quercus; it is published partly to call atten- 

 tion to the general desirability, as I see it, of designating hybrids by 

 binomials, and partly to facilitate a workable assemblage of oak 

 materials in herbaria. 



Lest misapprehension arise, it should be stated that what is here 

 called 0. rubra is the common red oak of the eastern United States; 

 though, following Professor Sargent's suggestion of a current mis- 

 identification, Mr. Ashe proposes replacing this name by Q. maxima, 

 and using rubra for what is here called 0. cuncata — the digitata or 

 falcata of many writers. 



- Proc. Nat. Acad. Sci. 2 : 626. 1916. 



