STANDLEY TREES AND SHRUBS OF MEXICO 1605 



or few, long-pedunc]ed, discoid, ochroleucous or tinged with purplish, about 1.8 

 cm. high; phyllaries very unequal, linear; achenes nearly linear, densely pu- 

 bescent, about 7 mm. long; pappus of about 13 Hnear acutish hyaline paleae 

 about 5.5 mm. long. 



97. BAHIA Lag. Gen. & Sp. Nov. 30. 1816. 



Reference: Rydberg, N. Amer. Fl. 34: 34-37. 1914. 



Herbaceous or suflfrutescent, usually cinereous or canescent-pubescent; leaves 

 opposite, at least below, usually dissected; heads yellow, radiate, solitary at tips 

 of branches or cymose-panicled; involucre 2 or 3-seriate, subequal, the inner 

 phyllaries often with scarious colored tips or margins; achenes very slenderly 

 clavate, substipitate, 4-angled, hirsute below, hirsutulous above; pappus of 

 about 8 hyaUne paleae, in ours rounded and with obscure or evident costa. 

 Leaves distinctly canescent-tomentose or canescent-pubescent beneath. 



Lobes of the leaves very narrow, often again lobed, usually more than 3. 



1. B. absinthifolia. 



Lobes of the leaves linear-lanceolate to cuneate, usually 3 and entire. 



la. B. absinthifolia dealbata. 

 Leaves green or slightly cinereous beneath. 



Pappus paleae suborbicular, nearly as wide as long 2. B. pringlei. 



Pappus paleae obovate, much longer than wide 3. B. xylopoda. 



1. Bahia absinthifolia Benth. PL Hartw. 18. 1839. 



Coahuila and Durango to Aguascalientes and San Luis Potosi; type from 

 Aguascalientes. Arizona and Texas. 



Suffruticulose, up to 35 cm. high, cinereous-strigillose, whiter on the lower 

 side of the leaves; leaves petioled, 2 to 5 cm. long, pinnatisect, the segments 

 2.5 mm. wide or less; heads several, pedunculate, about 1.8 cm. wide; involucre 

 about 6 mm. high; achenes 4 mm. long; squamellae obovate, 1.5 mm. long. 

 la. Bahia absinthifolia dealbata A. Gray, PL Wright. 1: 121. 1852. 



Bahia dealbata A. Gray, Mem. Amer. Acad. n. ser. 4: 99. 1849. 



Picradeniopsis dealbata Woot. & Standi. Contr. U. S. Nat. Herb. 16: 192. 

 1913. 



Chihuahua, Coahuila, and Durango; type from valley between Mapimi 

 and Guajuquilla, Chihuahua. Texas to Arizona. 



Similar, but with less divided leaves with broader segments, these sometimes 

 pannose-tomentose. 



2. Bahia pringlei Greenm. Proc. Amer. Acad. 32: 309. 1897. 

 Hidalgo; type from Tula. 



Suffruticulose, procumbent at base, with slender rootstocks; stem cinerous- 

 strigillose; leaves 2 to 3.5 cm. long, twice or thrice ternately pinnatisect, with 

 narrowly linear divisions; heads about 2 cm. wide. 



3. Bahia xylopoda Greenm. Proc. Amer. Acad. 34: 577. 1899. 

 Bahia ehrenbergii Schultz Bip.; Rydb. N. Amer. Fl. 34: 35. 1914. 

 Hidalgo; type from Pachuca. 



Very similar to B. pringlei except for the difference in pappus. 



98. LOXOTHYSANUS Robinson, Proc. Amer. Acad. 43: 43. 1907. 



Low shrubs; leaves opposite, broad, crenate or repand, slender-petioled; 

 heads white, discoid; involucre 2-seriate, equal, the phyllaries subherbaceous, 

 somewhat thin-margined and often with somewhat yellowish tips; achenes as in 

 Bahia; pappus oblique, of about 8 paleae, the innermost longest, sometimes 

 aristiform, the others blunt, the outermost shortest. 



The following treatment includes all the known species. 



