172 



GREENE 



branches, R. tyfihina, was by this time well known by Bauhin's 

 description of it, and had perhaps already appeared in some 

 gardens in Europe. In 1726 both the hairy and the smooth 

 sumachs were to be found in some London gardens and parks, 

 and in 1732 Dillenius published a folio plate and a full descrip- 

 tion of what must apparently stand for the R. glabra Linn, 

 of 1753- 



CHARACTERS FOR SEGREGATE SPECIES. 



Linnaeus' statement of the characters of Rhus glab?'a reads 

 thus : " Leaflets pinnately arranged, lanceolate, serrate, glabrous 

 on both faces." This is the same as no description at all. If one 

 assume said compound leaf to be odd-pinnate rather than equally 

 pinnate, one does so without any warrant in any word that 

 author said about either the species or the genus. Equally 

 without warrant will be any assumption that the leaf is of 7 

 leaflets, or that it is of 17, or of 27. Linnaeus gives no hint of 

 its character in these most significant particulars. One will also 

 reasonably infer that the leaflets are not notably pointed at the 

 upper end ; and whether at base they be stalked or sessile you 

 have no means of judging. It must also be assumed that there 

 is no distinction of coloring noticeable respecting the two faces of 

 the leaf; also whether of a dark-green, or of a bright-green, 

 or of a glaucous or blue-green, one is not informed. Such a 

 description as Linnaeus gives of Rhus glabra might easily apply 

 to each one of five species, or of fifty, or of five hundred species 

 in a genus. It is therefore worthless for diagnostic purposes. 



Coming down from the middle of the eighteenth century to 

 near the close of the nineteenth, we shall find that in American 

 books of American botany the Linnaean diagnosis of R. glabra 

 has met with a little amendment. That in Gray's Manual in 

 1890 reads thus : " Smooth, somewhat glaucous ; leaflets 11-31, 

 whitened beneath, lanceolate-oblong, pointed, serrate." The 

 expression, " whitened beneath," is one that helps us to fix on 

 certain shrubs, mostly southern, as representing this author's R. 

 glabra; but in New England there are at least two different 

 sumacs which this phrase completely excludes ; one of them, 

 inhabiting Massachusetts, shows not even a trace of bloom on 

 the lower face. Both of these, and with them several more 



