BOTANICAL BULLETIN. 43 



soil may account for its absence. The trees of the county in size compare favor- 

 ably with those of otlier counties I have examined. Farjus ferruginea, Liriodendron 

 Tulipifera. and Plattnnts occidentals do not attain the size here that they do in the 

 more southern counties. But on the otlier hand the Quercl. far exceed their kins- 

 men, here becoming true monarchs of tlie forest. I have had no opportunities for 

 extended measurements, yet I have on my list two of this genus with a diameter 

 exceeding 7 feet, two exceeding feet and seventeen exceeding 5 feet. A striking 

 feature to my mind is the young growth of Juglans nigra, L., which of late years 

 is springing up every where. I have not found a single instance in which it has 

 been cultivated and yet in one case I counted in a forest not exceeding 10 acres in 

 area, 165 representatives of this species, from 6 to 12 inches in diameter. I have 

 noticed the same fact in Grant county. This seems a strange fact, the more so 

 since the older growth where it occurs contains but few individuals, nor do the 

 stumps indicate that it ever had any great predominance. I would like to know 

 whether this has been noted in any other locality.— M. S. Coultek, Logunsport, 

 Ind. 



The Oaks of the United States. By Dr. George Engelmann.— In this 

 pamphlet of twenty pages read before the Academy of Science of St. Louis, March 

 20, 1876, Dr. Engelmann, in his usual happy style, has let a flood of light upon a 

 very dark and perplexing genus. The Oaks, with their endless forms, have long 

 been a puzzle and it should be a great relief to amateurs when a botanist of such 

 acknowledged keenness of observation takes hold of the sul)jcct, and while guiding 

 us to some extent in the straiglit, clear path through these intricacies, at the same 

 time acknowledges the difficulties in the way. The author first calls attention to 

 the "striking example of the deceptive polymorphism" of western oaks furnished 

 by the common Rocky Mountain scrub-oak. Xo fewer than 4 or 5 species have 

 been founded upon the different forms of this scrub-oak. "In herbarium speci- 

 mens they all appear distinct enough, but, looking around us the very abundance 

 of material must shake our confidence in our discrimination : within the compass 

 of a few hundred yards we find not only tlie forms above distinguished, but num- 

 bers of others which are neither the one nor the other, but which are intermediate 

 between them and clearly unite them all -is forms of one single extremely poly- 

 morphous species. If one oak behaves thus, why not others'? Thrown into a sea 

 of doubt, what can guide us to a correct knowledge?" The author then takes up 

 in detail the various features that are of use in determining the groups and species. 

 He considers the trunk — its bark as well as its wood — and remarks that the "pop- 

 ular distinction of "White-oaks' and 'Black-oaks' is based on correct observation," 

 The leaves are then considered, principally as to their vernation and the author 

 states it as his belief ''that the characters of vernation will not onlj'^ lielp to dis- 

 tinguish allied species or doubtful varieties, but will also assist in unravelling the 

 intricate questions of hybridity." The male flowers, female flowers and fruit are 

 spoken of in turn with their importance for furnishing valuable characters to dis- 

 tinguish the groups and species. In conclusion the author observes that our oaks, 

 leaving out the very peculiar Californian Q. densijlora, "arrange themselves into 

 two great groups, alluded to above as the White-oaks and Black-oaks. 



The White-oaks are characterized by paler, often scaly bark, tougher and den- 

 ser wood, and sessile or subsessile stigmas, and bear the abortive ovules at the base 

 or rarely on the side of the perfect seed. Besides this, the leaves and their lobes 

 or teeth are obtuse, never bristle-pointed, though sometimes spinous-tipped ; their 

 stamens are more numerous, the scales of the cup more or less knobby at base, the 

 inner surface of the nut glabrous or (rarely) pubescent; the fruit generally ma- 

 tures in the first year. 



The Black-oaks have dark, furrowed bark, brittle and porous wood, styles long 

 and spreading or recurved, abortive ovules alwaj-s near the tip of the perfect seed. 

 The leaves and their lobes are bristle-pointed, at least in youtli; lobes and teeth 



