I9I2.] TRELEASE— CLASSIFICATION OF BLACK OAKS. 169 



panying plates: the first (PL X.) with large hairy buds and rather 

 large fruit with coarse cup-scales, the second (PI. XL) with medium- 

 sized nearly smooth buds and moderate or large fruit with rather 

 closer or finer scales, and the third (PI. XII.) with still smaller buds 

 and acorns, these with still closer and finer cupule-scales. That the 

 groups are closely allied is to be expected, and in bud and cup char- 

 acters Q. coccinea connects the first two ; but a glance at the plates 

 will show how distinct the collective impression produced by each 

 group is, and how far from natural it is to place Q. marilajidica (PI. 

 X., f. i) next 0. nigra (PI. XII., f. 2) because of a compara- 

 bility in leaf shape that has worked mischief in the names both have 

 borne, or Q. pahistris (PI. XII., f. i) next Q. rubra (PI. XL, f. 5) 

 or O. vchitina (PI. X., f. 4), or to separate O. Catesbcci (PI. X., 

 f. 2) far from 0. digitata (PI. X., f. 3) or even Q. marUandica, 

 as is commonly done. An interesting feature in the cup of these 

 latter species is that the scales are inflexed around its margin — com- 

 monly in the first, occasionally in the others — a character to be con- 

 nected with Engelmann's observation^^ that the tips of the leaf lobes 

 are bent in in vernation in Catesbcci, though it is not absolutely lim- 

 ited to them. 



Though homogeneous in external bud and fruit characters, the 

 group of swamp oaks is subdivisible into a series with broad-lobed 

 leaves, the water oaks, in which the leaves are flatly imbricated in 

 the bud as in the black and scarlet oaks, and a series with narrow 

 entire leaves, the willow oaks, in which the leaves are revolute in 

 the bud — strongly so in Q. imbricaria, 0. Phcllos, Q. latirifolia and 

 Q. pwnila; less rolled in Q. cinerea and Q. myrtifolia, and thus 

 approaching the western groups, though the fruits of the two are 

 very dififerent. Such Mexican bristle-leaved oaks as Q. Grabami are 

 evidently of this general stock. 



Grouped primarily according to the characters here selected rather 

 than leaf form, these oaks fall into line as follows: 



Black Oaks. 



Quercus marUandica (black jack). 

 Quercus Catesbcci (turkey oak). 

 " Engelmann, /. c, 376. 



