120 Standley — Wootonella, a New Genus of Carduaceae. 



from the genus Ximenesia, to which it is most closely related, 

 that it seems worthy of generic rank. It is a perennial, propa- 

 gating by slender rootstocks, while all the species of Ximenesia 

 are annuals and of much greater stature. The paleae of the 

 disk are very narrow (almost filiform) and persistent, rather 

 than broad and deciduous. The wings of the achenes, also, 

 are corky-thickened at the apex, while in Ximenesia they are 

 comparatively thin. The most conspicuous difference is to be 

 found in the development of tbe achenes: in Ximenesia all 

 the flowers are fertile, while in this the disk flowers are sterile. 



The genus is named for Mr. E. O. Wooton, who first col- 

 lected the plant in good fruit, near Artesia, New Mexico, in 

 1905. It is appropriate that a plant peculiar to the Southwest 

 should be named for one who has done more than any other, 

 or almost more than all others combined, to make known the 

 flora of New Mexico. A genus Wootonia, also of the Cardu- 

 aceae, named by Dr. E. L. Greene in 1898, proves to be the 

 same as the older Dicranocarpus. 



Wootonella Standley. 



Low perennial, 20 cm. high or less, with slender deep-seated rootstocks; 

 stems slender, simple or branched, ascending, canescent; lower leaves 

 opposite, the upper alternate, 3 to 5 cm. long, irregularly dentate, nar- 

 rowed into winged petioles, these mostly dilated and dentate at the base; 

 heads large, 15 to 20 mm. broad, solitary, on naked terminal peduncles; 

 bracts foliaceous, canescent, 8 to 15 mm. long, more or less unequal; 

 rays rather pale yellow, conspicuously exceeding the involucre, toothed 

 at the apex; ray flowers fertile, the disk flowers sterile; paleae very 

 narrow, nearly filiform, persistent; achenes obovate or oblong, villous, 

 broadly winged, the wings corky-thickened near the apex; pappus none. 



Wootonella nana (A. Gray) Standley. 



Ximenesia encelioides nana. A. Gray, PI. Wright. 2: 92. 1853. 

 Yerbesina nana B. L. Robinson, Proc. Amer. Acad. 34: 543. 1899. 



The following specimens have been examined. 



Texas: Kent, 1902, Tracy & Earle 385; Mexican Boundary Survey 589. 



New Mexico: Artesia, August 2, 1905, Wooton. 



Mexico: La Ventura, Coahuila, 1896, E. IV. Nelson 391S. 



The New Mexican specimens are the only ones seen in which the heads 

 are fully developed. The collections of the Mexican Boundary Survey 

 are very immature. Specimens of this plant are rare in collections; but 

 it is said to be a common weed in cultivated, usually alkaline, fields of 

 the Pecos Valley. 



