130 University of California Publications in Geological Sciences 



Quercus renoana n. sp. 



(PI. 23, figs. 4-6) 



Description. — Leaves ranging from oval to oblong; tips rounded to acute, bases subrounded to 

 truncate; length from 2.5 to 4.0 cm., width from 1.0 to 2.0 cm.; petiole heavy, ranging from 

 2 to 4 mm. in length; midrib stout below, tapering above, and relatively straight; 9 to 11 sub- 

 parallel secondaries in oval and oblong leaves, fewer in subsinuate leaf, diverging at moderate 

 angles, looping evenly upward along margin; tertiaries comparatively coarse, trending nearly 

 normal to secondaries at point of departure, but then becoming somewhat branching and irregu- 

 lar ; finer mesh generally quadrangular or polygonal ; margin entire to subsinuate ; texture heavy. 



Discussion. — Three leaf impressions in the flora resemble those produced by the 

 living Q. engelmannii Greene of interior southern California, and Q. oblongifolia 

 Torrey of the southwestern United States and adjacent Mexico. The finer details 

 of nervation are similar, and close relationship is apparent in the variation in 

 shape, which ranges from long-oval to oblong, and in the margin, which varies from 

 entire to subsinuate. In addition, the rather numerous, essentially subparallel 

 secondaries in the long oval leaves are like those of the living species, as is the 

 venation of the subsinuate leaf. 



Since there is considerable overlap in the leaf characters of some species of living 

 live oaks, the question may well be raised as to whether this material really repre- 

 sents a new fossil oak. The leaves of Quercus convexa Lesquereux partly overlap the 

 range of variation of these fossils, though in the large suite of material of Q. con- 

 vexa at Table Mountain none is subsinuate. The same may be said of Q. dayana 

 Knowlton, which is related to Q. convexa, though differing from it in that its norm 

 of variation is toward ovate leaves, not typically long-oblong and often nearly 

 linear-oblong ones. 



Quercus convexa and Q. dayana have been compared with Q. virginiana Miller 

 and its close relatives. There are resemblances, yet the differences are also pro- 

 nounced, chiefly the tendency of the secondaries in the fossils to be essentially sub- 

 parallel, whereas those of the virginiana phylad tend to depart at somewhat vary- 

 ing angles, and at lower angles. In addition, the secondaries of the virginiana 

 group are more irregular, and the nervilles make a finer mesh. Thus, although 

 Q. dayana and Q. convexa are no doubt closely related oaks, their exact relations 

 to the modern virginiana phylad are not wholly clear. Q. convexa has also been 

 compared with Q. oblongifolia and Q. engelmannii, though the range of variation 

 does not include the sinuate and occasionally toothed leaves. However, the entire 

 oblong leaves of Q. convexa appear to match the similar leaves of Q. engelmannii 

 and oblongifolia more closely than those of virginiana in finer nervation and in the 

 features of the subparallel secondaries and relatively strong intersecondaries. 



Since the virginiana and engelmannii phylads are related, it is possible that Q. 

 convexa and Q. dayana may not bear a direct ancestral relationship to the living 

 types, but may well represent offshoots that ended without further issue. The 

 limited evidence available suggests that Q. renoana, a member of this group, is 

 more nearly related to engelmannii than is Q. convexa or Q. dayana. It is apparent 

 that until more fossil material becomes available for study, the interrelationships 

 of these fossil and living oaks will continue to remain obscure. 



Occurrence.— Verdi, Nev.: U.C. Mus. Pal. (loc. P102), cotypes, nos. 2013-2015. 



