OF ARTS AND SCIENCES : MAY 13, 1873. 637 



Chrysothamnus, Nutt. This is the name adopted in the Genera 

 Plantarum for the group containing not only the Chrysothamnus of 

 Nuttall, and all the species which I have at various times generically 

 combined with it under the name of Linosyris (Schlechtendal having 

 led the way with a Mexican species), but also Bigelovia DC, as re- 

 stricted in Torr. & Gray's Flora. All this consolidation is evidently 

 necessary, as also the separation of these American species from 

 Linosyris of the Old World, the species of which, by the occasional 

 production of heterochromous rays, are now proved to belong to 

 Galatella, i. e. to Aster in the largest sense. But Chrysothamnus is a 

 much later name than Bigelovia, which, as Bentham cursorily indicates 

 in the appendix, is to be adopted. The genus, as now received, is 

 nearly as polymorphous or composite as Aplopappus itself, from which 

 at more than one point it is quite arbitrarily separated. On the other 

 hand, it is as arbitrarily distinguished from the Euthamia subgenus of 

 Solidago, B. diffusa and B. arborescens sometimes developing a small 

 ray or two. As these species have lanceolate or even broader style- 

 appendages, achenia which are not very slender and taper to the base, 

 and ampliate rather deeply cleft limb to the corolla, we have to rely 

 upon the unequal bristles of the pappus and the woody habit to keep 

 them out of Solidago. The typical Bigelovia and all the genuine 

 Chrysothamni partake of the character which is so strikingly displayed 

 in B. pidchella, Bigelovii, and depressa, namely, the imbrication of the 

 scales of the involucre in five (rarely four) strict vertical ranks. The 

 slender style-appendages of Ericameria also characterize the section 

 Chrysothamnus and another group which lies between the two ; while 

 the original Bigelovia has the style as well as the habit of Solidago, 

 section Euthamia. The cusp in the centre of the receptacle of B. 

 nudata occurs (sometimes in a more chaffy form) in the original speci- 

 mens of B. Bigelovii, also in those recently received from Mr. Greene, 

 but not in those collected by Dr. Parry ; and it is represented by some 

 chaff-like extensions of the alveoli in B. Bolanderi, as also by the 

 setiform elongated frimbrillae in B. diffusa. The achenia are at least 

 5-nerved in almost all the species ; several have intermediate, usually 

 more slender nerves. 



In the subjoined revision, the first section ends with species which 

 are ambiguous between Bigelovia and Solidago, and the whole with 

 the better characterized but very Soliclagineous original species. 



