1568 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Shrub; branches densely sordid-pilose with spreading hairs, glabrate; leaves 

 subsessile, ovate, 5 to 6 era. long, 2.8 to 3.5 cm. wide, acute, shallowly cordate at 

 base, roughish above, strigose and strigillose beneath; heads small, in umbelli- 

 form cymes; pedicels 6 to 27 mm. long; involucre 8 mm. high, strongly graduate, 

 the phyllaries ovate to oval, appressed, the outermost acute, the others obtuse. 



17. Zexmenia seemannii A. Gray, PI. Wright. 1: 114. 1852. 



Sonora, Sinaloa, Durango, and Tepic; type from Cerro de Pinal, Sinaloa. 



Shrub about 1 meter high; branches strigillose; petioles 3 to 10 mm. long; 

 blades linear-elliptic to linear-oblong or oblong-lanceolate, 4 to 10 cm. long, 7 to 15 

 mm. wide, obtuse to acuminate, cuneate at base, strongly 3-nerved, shining, 

 sparsely strigose or strigillose; heads medium-sized, in terminal umbelliform 

 cymes of 3 to 5, the pedicels 12 mm. long or usually less; involucre 1 to 1.2 cm. 

 high, strongly graduate, the phyllaries mostly suborbicular-oval to oblong, the 

 rounded outer and middle ones with short, thick-herbaceous, rather loose tips. 



18. Zexmenia lantanifolia (Schauer) Schultz Bip. in Seem. Bot. Voy. Herald 

 306. 1856. 



Lipochaeta lantanifolia Schauer, Linnaea 19: 729. 1847. 



Tamaulipas and San Luis Potosi to Hidalgo; type from Zimapdn, Hidalgo. 



Shrub; branchlets spreading or ascending-hispidulous, glabrate; petioles 5 to 

 10 mm. long; blades ovate, 1.8 to 4.5 cm. long, 1 to 2.8 cm. wide, acute, cuneate to 

 truncate or subcordate at base, rough above, hirsute or hispid and often griseous 

 beneath; heads solitary, leafy-bractcd, rather large, the peduncles 2.5 to 7.5 cm. 

 long; proper involucre 8 to 10 mm. high, campanulate-subglobose, the phyllaries 

 ovate to lance-oblong, mostly acute or acuminate, the outer with usually appressed 

 herbaceous tips. 



19. Zexmenia pringlei Greenm. Proc. Amer. Acad. 33: 489. 1898. 

 Puebla; type from Tehuacdn. 



Shrub; branchlets canescently arachnoid-tomentose, glabrescent; petioles 

 about 5 mm. long; blades deltoid-ovate, 1.3 to 3.5 cm. long, 1 to 2.5 cm. wide, 

 acute or obtuse, cordate at base, rugose and green above, canescently lanate- 

 tomentose beneath; heads solitary, rather large, leafy-bracted, the peduncles 

 5 to 17 cm. long; proper involucre about 10 mm. high, the inner phyllaries oblong, 

 acute or acuminate, arachnoid-ciliate. 



20. Zexmenia gnaphalioides A. Gray, Proc. Amer. Acad. 15: 36. 1879. 



Known only from the type localitj^ between San Luis Potosi and Tampico. 



Shrub, floccose-lanate; leaves short-petioled, deltoid-ovate or cordate-lanceo- 

 late, 1.2 to 1.8 cm. long, acute, entire, revolute-margined, above sericeous-his- 

 pidulous, beneath pannose-tomentose; heads solitary, about 1.2 cm. thick, leafy- 

 bracted, on long peduncles; phyllaries oblong to linear, obtuse, appressed. (De- 

 scription compiled.) 



21. Zexmenia brevifolia A. Gray, PI. Wright. 1: 112. 1852. 



Chihuahua and Coahuila, south to Zacatacas and San Luis Potosi. Texas; 

 type collected between the Limpio and Rio Grande. 



Shrub about 1 meter high, cinereousiy strigillose or retrorse-hispidulous; 

 leaves short-petioled, suborbicular to ovate, 1.8 cm. long and 1.3 cm. wide or 

 smaller, obtuse or rounded, broadh' rounded to subcordate at base, entire, harshly 

 tuberculate-strigillose or hispidulous; heads medium-sized, solitary, long- 

 peduncled; involucre 6 to 10 mm. high, subequal or graduate, the outer and middle 

 phyllaries mostly obovate or spatulate, the tips herbaceous, spreading. 



22. Zexmenia strigosa (DC.) Schultz Bip. in Seem. Bot. Voy. Herald 306. 

 1856. 



Lipochaeta strigosa DC. Prodr. 5: 610. 1836. 



Known only from the type locality, near Tehuantepec, Oaxaca. 



