74 University of California Publications in Botany. [ VOL - 3 



ceous save at the white-scarious base: rays 25 to 35 (60 to 80, 

 ace. to Gray), lavender, about 5 mm. long: disk-flowers yellow: 

 achenes 1'near ; those of the disk with 20 to 40 unequal pappus- 

 bristles. 



Lower Sonoran Zone : Warm Springs, near Newberry, Mohave 

 Desert, Parish, no. 1252 ; sand hills near Hector and near Bars- 

 tow, in the same district, Hall, nos. 6118, 6833 ; southern Arizona 

 and adjacent Mexico. 



21. MONOPTILON T. & G. 



Depressed desert annuals with short radiating or ascending 

 branches and upturned heads of daisy-like flowers. Involucre 

 campanulate, of equal linear bracts. Keceptacle naked, flat. 

 Rays conspicuous, normally white but often tinged with rose. 

 Disk yellow. Achenes narrowly obovate, compressed, nerved 

 along the margins, pubescent with emarginate hairs. Pappus 

 alike in ray and disk. 



As here treated, Monoptilon consists of but two species here- 

 tofore considered as constituting two distinct genera, mainly 

 because of a difference in their pappus characters. But these 

 characters are more variable than was formerly supposed, the 

 only constant differences being a minute coroniform toothed 

 pappus with a single plumose awn, in the one case, and a palea- 

 ceous pappus with 1 to 12 scabrous awns, in the other. The disk- 

 flowers are also more conspicuously villous in the first species 

 than in the second. But in all other characters, in general aspect, 

 and in distribution, the two are very similar, and may therefore 

 be received into a single genus. 



Pappus-awn solitary, short-plumose 1. M. bellidiforme. 



Pappus-awns 1 to 12, not plumose, alternating with paleae 



2. M. bellioides. 



1. M. bellidiforme T. & G., Journ. Bost. Soc. Nat. Hist. v. 

 106, t. 13 (1847). 



Stem much branched, the branches commonly spreading and 

 seldom over 5 cm. long: herbage villous-hirsute : leaves spatulate 

 or linear-spatulate, 5 to 20 mm. long, alternate: involucre 5 mm. 



