92 MISSOURI BOTANICAL GARDEN. 



pass directly into 



grade 



into the simpler leaved variety barbatum, and it is also diffi- 

 cult to determine whether a very few herbarium specimens 

 go into barbatum or nigrum. Were it not for these, I 

 should agree with Professor Bailey in treating the latter as 

 a distinct species. All three forms have essentially the 

 same distribution, the variety nigrum being apparently a 

 little more restricted than the others, and the most western 

 form belonging to the variety barbatum rather than the 



type . 



The typical saccharum, which is evidently the plant of 

 which Wangenheim * figures a leaf under the name saccha- 

 rinum, is the variety pseudo-platanoides of Pax f and 

 Schwerin.| The description and figure in the several 

 editions of the Sylva of the younger Michaux leave no 

 doubt that what is here called variety nigrum is the tree to 

 which he applied nigrum as a specific name, and its extreme 

 forms are well represented by Schwerin,§ who, mistaking 

 for the true nigrum what I have called barbatum, as has 



many American 



names 



because of the green lower surface of the leaves. 



Following Professor Bailey, who has clearly indicated 

 the characters of nigrum, \\ I have tried to associate with 

 the leaf characters, others drawn from the inflorescence 

 and fruit ; but in this attempt I have failed, because of in- 

 sufficiency of well authenticated flowering specimens of the 

 different forms ( though I am disposed to think that good 



& 



t), and 



form 



am convinced 



Baytrag zur teutschen holzgerechten Forstwissenschaft, die Anpflan- 

 zung nordamericanischer Holzarten, mit Anwendung auf teutsche Forste f 

 betreffend, 1787, pi. 11, f . 26. 



f Engler's Bot. Jahrb. 1886, vii. 242. 



X Gartenflora, xlii. 455, f . 95, no. 1. 



§ I. c. 456, f. 95, nos. 6 and 7. 

 || Bot. Gazette, xiii. 214. 



5 



j 



