159 



A. ambigita DC. The first time it was really distinguished was in 

 Torrey & Gray's Flora ; but here the range is faulty, probably 

 because these authors followed Hooker in this respect, and Dr. 

 Pitcher's specimen belongs to Arabis lyrata. A somewhat better 

 description we find in Gray's Manual, sixth edition, and in the 

 Synoptical Flora ; but in both it is confused with the Rocky 

 Mountain plant, i. c, the species which we next discuss. The 

 first adequate description we find in Britton & Brown's Illustrated 

 Flora,* where it is also figured. This description, as well as that 

 in Britton's Manual, refers wholly to the eastern plant, but Alaska 

 and Oregon should be excluded from the range. 



Pilosella Novae-Angliae differs from Sisymbrium htimile Ledeb. 

 (Icon. PI. Fl. Ross. 2 : i6. //. 7^7. 1830) in the more compact 

 habit, the scant pubescence, the smaller flowers, the more slender 

 pod, and the longer style, which is about i mm. long. 



Dr. Robinson refers the plant to Braya, but the type of that 

 genus is so unlike this species both in habit and structure that 

 the present writer can not follow him in his views. Pilosella 

 Novae-Angliae has such a resemblance to P. TJialiana in many 

 respects that it would be hard to deny the relationship. The 

 structure of the pod is the same, the only difference being that the 

 minute reticulation of the septum in P. Novae-Angliae is shorter 

 and therefore approaches that of Braya. In habit, the main dif- 

 ference between the two species is that P. Thaliana is an annual, 

 while the present species is a perennial. 



The specimens at hand of P. Novae-Angliae are the following 

 from Willoughby Mountain, Vt. : July, 1887, Edzvin Faxon \ ; 

 1894, A. J. Grout, W. IV. Eg gl est on, & H. S.Jesnp ; 1892, i/. //! 

 Riisby ; 1866, H. Mann; 1881, C. G. Pringle. 



Pilosella Richardsonii Rydb. 

 Sisymbrium Jiumile (especially var. /9) Hook. Fl. Bor.-Am. i : 



62. 1830. Not Sisymbrium hum.ile Ledeb. 1830. 

 Braya hnmilis Robinson, Syn. Fl. i^ : 141, in part. 1895. 



This also has been confused with Sisymbrium humile Ledeb. 



*2: 116. / i6g8. 1897. 



f As no type has been designated under any of the synonyms given above, this may 

 be regarded as the type ; it is preserved in the Columbia University herbarium. 



