!S07] Hall. Compositor of Southern California. 247 



1. A. platyphylla Gray, Syn. Fl. i. pt. 2, 410 (1884). Mala- 

 cnthrix platyphylla Gray, Proc. Am. Acad. ix. 214 (1874). TO- 

 BACCO-WEED. 



Scape commonly 3 to 8 dm. high, obscurely striate, white and 

 shining, ending above in a diffuse cymose panicle : radical leaves 

 obovate, obtuse, sessile, 5 to 10 cm. long, 2.5 to 4 cm. broad, spin- 

 ulose-denticulate ; cauline leaves reduced to minute scale-like 

 bracts of the inflorescence : involucre 6 mm. high ; its bracts with 

 scarious margins: ligules about 1 cm. long, quadrate or oblong, 

 sharply 5-toothed at the truncate apex, white : achenes white, 4 

 mm. long, somewhat pubescent, the truncate apex with no trace 

 of a border ; ribs corky-thickened at maturity, 5 of them usually 

 more so than the others, rendering the achene obtusely 5-angled. 



A winter and spring annual, its period of flowering depend- 

 ing upon the rains, confined to gravelly mesas and washes in the 

 Lower Sonoran Zone of the Desert Area. Quite common on the 

 Colorado Desert, from Mecca east, and on the southern Mohave 

 Desert, from the Ord Mts. east, Hall, nos. 5834, 5854, 6033, 6084 ; 

 6126, 6246, 6814 ; Funeral and Grapevine Mts., Inyo Co., Coville 

 & Funston, nos. 576, 975 ; east to Arizona and Utah. 



105. MICROSERIS Don. 



Herbaceous plants, mostly acaulescent or short-stemmed, 

 glabrous or slightly puberulent. Leaves chiefly in a basal tuft, 

 pinnatifid with mostly linear and often falcate lobes, or entire 

 in the same species. Peduncles one-headed. Main bracts of the 

 involucre nearly equal but with short outer ones at base or un- 

 equal and loosely imbricated. Ligules short, yellow, inconspic- 

 uous in dried specimens. Achenes slender-fusiform, or turbin- 

 ate, or cylindric, ribbed, mostly truncate. Pappus-paleae 5 to 10. 

 each with a more or less elongated scabrous or short-plumose awn. 



Our first three species fall into the section Eumicroseris ( Calais 

 Eucalais DC.) ; the fourth and fifth into the section Uropappus 

 ( Calais Calocalais DC.) ; the last into the section Scorzonella. 

 These sections are treated by some authors as distinct genera, but 

 they are very similar in general appearance and it is difficult to 

 find constant technical characters of importance on which to 



