158 Recent Litcrattire, [zoE 



Nearly all the species reduced by Engelmann to forms of Q. 

 unditJata are restored, and a new one, Quercus vemcstu/a Greene, 

 added; Qitcrcits Jacobi is raised from the synonymy of \^. Garry- 

 ana to its former rank; and Quercus Gilberti pi. xxxvii Greene, 

 from an island in Puget Sound, is established on no better evidence 

 than the sterile shoot of a ** low trailing shrub." 



Dr. George Engelmann was a most painstaking and careful stu- 

 dent of our oaks and other difficult genera, and most of his writings 

 are the results of years of study and research. I resided many 

 years in southern Colorado and at Dr. Engelmann's request col- 

 lected for him the many forms of the variable oak so abundant 

 there, observed Its habits and endeavored to answer his many ques- 

 tions. At the time of his western trip, I had the pleasure of show- 

 ing him a locality where a multitude of forms were assembled in a 

 small area and as his own words describing it seem so appropriate 

 they are here quoted from Trans. St. Louis Acad, of Sciences, 

 vol. iii, 372, 1876. 



"A striking example of the deceptive polymorphism of these western oaks is fur- 

 nished by the common Rocky Mountain scrub-oak. This interesting species grows 

 on the foot-hills of the eastern slopes of the mountains of Colorado, sparingly near 

 Denver, scarcely north of that city, but abundantly southward, about the Pike's 

 Peak region, and thence extends through New Mexico eastward into Texas, and 

 westward through Utah and Arizona into southern California. Tho center of dis. 

 tribution perhaps, at all events the classical locality of this species, are the mount- 

 ains above Caiion City, in southern Colorado. In the valley and on the mountain 

 slopes q,bout this place the oak thickets abound, six to eight feet high, single trees 

 occasionally four to six inches thick, rising up to twelve or fifteen feet, rarely higher. 

 The leaves are three to four inches long, broadly obovate, deeply lobed, sometimes 

 pinnatifid, underneath stellate-pubescent; the broad lobes obtuse or retuse, often 

 again two to three lobed. They bear middle-sized or small oval acorns, in more 

 or less knobby hemispherical cups. Scattered copses of these broad-leaved oaks, 

 often of a beautiful brownish-purple in September, accompany us to within a few 

 hundred yards of the caiion, but here the character of these shrubs changes; the 

 bushes are lower, the leaves smaller and in outline narrower, the lobes narrower 

 and mostly undivided, but still obtuse. Now we near the precipice itself; from the 

 ragged dizzy edge we here and there get a glimpse of the young Arkansas, whose 

 clear, green waters toss and foam twelve or fifteen hundred feet under us, through 

 the inaccessible gorge, rushing toward the plains. The oak bushes accompany us 

 even here, but now they are only 4-6 feet high, with leaves two inches long, ovate- 

 lanceolate m outlme, no longer lobed, but coarsely dentate, the acute teeth termi- 

 nating m a sharp point; the acorns are scarcely different from those noticed before. 

 A few steps more, and we have reached the brink of the precipice itself; oak bushes 

 here too, but only three or four feet high, with small (one inch long), oval, firm, almost 



