1908] Rhus Glabra in Canada? 181 



the Appalachian divide between Virginia and Long Island. If 

 by any magic a clump of this shrub should be transferred to 

 western New York, or across into Ontario, and set down 

 adjacent to the so-called Rhus glabra of those regions, the first 

 botanist who came upon it, seeing the wonderful contrast in 

 foliage, would be likely to suspect that in this Rhus of such 

 enormous foliage he had a new species. The shrub of the regions 

 north of the Alleghenies has never two-thirds as many leaflets, 

 and these never nearly as large, so that its leaf, as a whole, is not 

 of half the size — certainly seldom as much as half as large — as 

 that of the real Linnaean Rhus glabra. It is as common from 

 Ithaca, New York, to the vicinity of Boston, Massachusetts, 

 as Rhus glabra genuine is in Virginia, southern Pennsylvania and 

 •New Jersey; and these marks of the leaves are not all. Let 

 us place the two shrubs in closer contrast descriptively. The 

 one of the North, copious about Ithaca, and extending into 

 Ontario, we will call Rhus Ithacensis. 



Rhus glabra. 



Leaf as a whole commonly 2 

 feet long. 



Leaflets 17-25, rounded at 

 base, 4-6 inches long, of 

 hard firm texture. 



Fruiting panicle with verv 

 short, stout peduncle. 



Panicle itself between fusi- 

 form and pyramidal, com- 

 monly 10 inches high; 

 drupelets large. 



Leafy branches of shrub quite 

 blue with bloom. 



Rhus Ithacensis. 



Leaf as a whole usually 7-11 

 inches long. 



Leaflets 11-17, abruptly taper- 

 ing at base, 2h or rarely 

 3 inches long of thinner 

 texture. 



Fruiting panicle with long 

 peduncle and not stout. 



Panicle oblong-fusiform Ah-b 

 inches high, the drupelets 

 smaller. 



Leafy branches much more 

 slender. merely glaucescent. 



If such marked distinctions exist between the northern 

 smooth sumachs and the southern, then, in the name of science, 

 not to say of common truthfulness, the expression "Rhus glabra, 

 Linn." should early disappear from the books and lists of 

 Canadian plants. No kind of procedure is more subversive of 

 knowledge than that of transferring the name of one object, to 

 another object very unlike that to which alone the name by 

 right belongs. 



I conclude by repeating it, that this Rhus glabra case is but 

 illustrative of a certain principle. Under that revival of interest 

 in North American botany that is now in progress, old and 

 deeply rooted errors about the identity of things are being 

 perfectly indicated, and the amendments of them made, by the 

 score every year, but curiously, the botanists are of two classes, 

 those who welcome the fuller knowledge, and those who deplore 

 and o}>pose it. 



