CALIFORNIA ACADEMY OF SCIENCES. 85 



botany, show that even in this plant the five bristles are as 

 commonly present in their fullest development, as in any spe- 

 cies of the white- and purple-flowered section. It is equally 

 in all these, a rare and exceptional case that they are reduced 

 or wanting. That these three species have their rays, when 

 present, clear white or purplish, with never a tint of yellow, 

 whereas the original Pentaclncta and its fine newly discov- 

 ered cognate has them golden yellow, seems almost to 

 require the reinstatement of Aphantochaeta as a genus of 

 three species; yet the plants are all so perfectly alike in 

 habit, as well as the character of akene and pappus, that it 

 seems best to separate them only sub-generically. The un- 

 fortunate misapplication of the specific name exilis should 

 no longer be left uncorrected, and in the subjoined re-arrange- 

 ment of the species, it is dissevered from its connection with 

 the one to which it has misleading!}* been applied, and is 

 bestowed upon that excellent one which claims it. 



§1. Eupentachseta. 



Rays golden yellow: pappus apparently always well developed; 

 bristles 5 — 12; akenes not compressed. Plants of the south 

 part of the State; afoot or less high. 



P. aurea, Nutt. 



Involucre glabrous: bristles of pappus 5.— Trans. Am. 

 Phil. Soc. VII. 336. Torr. & Gray, Fl. N. Am. II. 249. 

 Gray, Bot. Cal. I. 305. Syn. Fl. 120. 



Common on plains towards and around San Diego. 



P. Lyoni, Gray. 



Involucre hirsute: pappus bristles 9 — 12. — Syn. Fl. 445. 



§ 2. Aphantochaeta. 



Bays (when present) white (reddish outside), never yellow or 

 even ochroleucous: pappus-bristles 3 — 5; in each species occa- 

 sionally reduced or obsolete; akenes slightly compressed. Plants 



