494 BROOKLYN BOTANIC GARDEN MEMOIRS 



Miocene oaks, of California, has been held to be varietally related 

 to the existing golden oak of California, and is known as Quercus 

 chrysohpis montana; but little can be said for or against this reputed 

 relationship. Except for this, none of the Miocene oaks is thought 

 to have survived. 



Little is known of the Pliocene in North America, and it may be 

 that the sparing deposits in Maryland and Alabama that are supposed 

 to be of this horizon may be open to some question whether they are 

 not of more recent age. The 4 nominal species of Quercus that have 

 been found in them are distinctly more like modern oaks than any- 

 thing that preceded, but identities with existing species are not 

 clearly evident to me (7). In South America, several fossil oaks from 

 the Pliocene have been described, not evidently related to existing oaks, 

 from localities far from any existing species (8). At present only 

 four oaks occur in South America; these, which grow in the interior 

 mountains of Colombia, form a natural group which appears more 

 closely related to some of the Costa Rican oaks than to any others that 

 are now known (9). 



If the term Pleistocene be used to designate glacial or later deposits 

 in which fossils are found, it is to be assumed that these fossils will 

 be very similar to if not identical with existing species. Scattered 

 deposits of this kind have been examined from various points in the 

 Atlantic region^ — Canada, New Jersey, Pennsylvania, Maryland, 

 Virginia and Kentucky; and from California in the Pacific region. 

 From these deposits 20 oaks have been named. Two of them, Q. 

 predigitata Berry and Q. pseudo-alba Hollick, are separately designated 

 as the ancestral forms respectively of Q. digitata or f ale ata and Q. alba, 

 both of which are held to be represented by other Pleistocene material. 

 A third, Q. abnormalis Berry, may have been a teratological bifid form 

 of Q. Phellos, which is known in its normal form from Pleistocene 

 deposits. Concerning a fourth species, Q. Glennii Hollick, I must 

 admit a serious doubt as to the horizon to which it is ascribed. The 

 remaining 16 species, into which I have merged Q. abnormalis, Q. 

 predigitata and Q. pseudo-alba, are easily identified with species now 

 living in the regions in which they have been found fossilized and, as 

 would be supposed from this, all of these Pleistocene oaks are from 

 the Atlantic region, except Q. chrysolepis, which was collected in 

 California. 



Even a cursory inspection of the many illustrations of fossil oaks 

 that have been published shows that collectively or for any given 

 period they present a multiplicity of leaf forms more or less com- 

 parable with what is known for existing species; indeed Professor 

 Cockerell, who has given much attention to the point, finds in Quercus 



