14 



The acorns vary considerably. Those of Phellos are nearlv glob- 

 ular with a low, saucer-like cup (Fig. i in the cut) ; in nigra ovoid 

 or oblong with a top-shaped cup (Fig. 5). In the hybrid they vary 

 on the different trees; the one represented in Fig. 2 came from the 

 tree bearmg the leaves figured 2 and 3 in Plate x ; it is seen to be 

 slightly longer than the acorn of Phellos, and to have a slightly deeper 

 cup with broader scales. The acorn represented in Fig. 3 grew with 

 leaves like those figured 4, 5, 6 and 7 ; this is much deeper-cupped 

 and longer, with broader scales. The trees which bore leaves like 

 those figured 9 and 10, had acorns like the one represented in Fig. 4 



'^'t\ ^^^ ^^ ^^^°^^- °^°'^ i" shape,with a very wide broad-scaled 

 cup, and does not seem to be intermediate between those of the 

 parents, but is peculiar to itself. 



?A-5^# 





Fiar.i. ris.2. Fig. 3. Pig. 4. pjg^B, 



_ The primary venation, .which is simply pinnate, with short veins 

 in Fhellos, and irregularly-pinnate, with veins of very unequal length 

 in «^^r^, presents every variation between the two in the leaves of 



the nvhrin 



the hybrid. 



The Plates do not represent, by any means, all the variations 



— 7 



mon forms which occur. 



ct)m 



hl.I b^a^k o/the hybrid trees is most nearly like that of nigra, being 

 black and quite rough, though varying somewhat in the different trees 

 I have thought It not improper to name this hybrid oak— probably 



Mr ^W "S p''^'^'"' all-after the gentleman who first discovered it! 

 Mr. W. H. Rudkin. ' 



In connection with this subject, I take the liberty of making the 

 following extracts frorn Dr. Geo. Engelmann's paper on *'' The Oaks 

 ot the United States, in order to enumerate the hybrids already 



bHTo r ' r'^i'-'^- ^'- E-gelmann says : '' White oaks and 

 black oaks are too distinct to be crossed. * * * Amnna thp 



white oaks, hybrids seem to be much rarer than among black oaks 



must, I believe, be referred here. careiui ODserver 



Q.alba^Prifius. K single tree, now unfortunately destroved 

 was observed by Dr. G. Vasey near Washington. ^ destroyed, 



Ij^jj^y^lli^l^gj^^kjar e much more numerous or 



• Trans. StTEouis Amd. Set., Vol. iii, Nos. slIi^dTir 



* * * 



