﻿114 Hall: Notes on Baeria and Lasthenl\ 



leaves in these specimens are flat and i mm. wide; the bracts 

 have each a strong midrib paralleled by two other ribs exactly as 

 in the type of B. platycarpha except that the midrib is slightly 

 more prominent. Although there is some variation in the shape 

 of the involucral bracts, this cannot be correlated with other 

 characters. For example, Dr. Greene's Vallejo plants of B. 

 carnosa have bracts with an outline exactly like those of his Byron 

 Springs specimens which have pinnatifid leaves and which must 

 therefore be accepted as B. platycarpha. 



§ Dichaeta 



This section is distinguished from all the preceding by its uni- 

 formly dimorphous pappus. However, the achenes are sometimes 

 entirely devoid of pappus in plants which are otherwise exact 

 counterparts of the pappus-bearing forms. It is thus seen that the 

 character of these structures when present is of more importance 

 than their mere presence or absence, a principle which holds in 

 other groups as well. Furthermore, this regular alternation of 

 the two kinds of pappus-scales on a single achene in species of 

 Dichaeta is of much greater significance than are the irregular 

 and fluctuating pappus-forms in some species of Eubaeria and 

 Ptilomeris. 



B. tenella (Nutt.) Greene is undoubtedly an ecologic form of 

 B. uliginosa (Nutt.) A. Gray. Specimens at the Herbarium of 

 the Philadelphia Academy of Sciences, indicated as types by 

 Nuttall, plainly belong to the well-known dwarf form of somewhat 

 gravelly or scarcely alkaline soil, while the more robust and succu- 

 lent form which represents typical B. uliginosa grows on lower and 

 more or less alkaline ground. Slender specimens of B. Fremontii 

 have been often labeled B. tenella, and this error has led to con- 

 fusion concerning the proper status of the latter form. 



With B. Fremontii (Torr.) A. Gray is included not only B. 

 Burkei Greene, a form in which the pappus-bristles are reduced to 

 one, but also Lasthenia conjugens Greene, the species which at one 

 time led Dr. Greene to unite the two genera. This latter species 

 was originally distinguished by the united bracts of the involucre 

 and the polished olive-green achenes. In the herbarium of the 

 University of California are two specimens of the type collection 



