STANDLEY TREES AND SHRUBS OF MEXICO 1565 



Involucre shorter, or else the phyllaries not with ovate base and abruptly 

 narrowed, long, herbaceous tips. 

 Involucre in anthesis 1 cm. thick or more; phyllaries broadly ovate 



or oval, with squarrose, herbaceous tips 4. Z. squarrosa. 



Involucre in anthesis less than 1 cm. thick; phyllaries usually ovate 

 and without squarrose herbaceous tips. 



Achenes with true wings 23. Z. scandens. 



Achenes not with true wings, but usually narrowly wing-margined. 

 Young branchlets densely spreading-hirsute.5. Z. michoacana. 

 Young branchlets sparsely strigose or nearly glabrous. 



6. Z. elegans. 



1. Zexmenia ghiesbreghtii A. Gray, PI. Wright. 1: 113. 1852, as Z. ghies- 



brechtii. 



Sinaloa to Guerrero; type from Mexico, without definite locality. 



Suffrutescent (?), 1.3 to 3 meters high; stem strigillose; leaves subsessile, ovate 

 or lance-ovate, mostly 9 to 13.5 cm. long, 2 to 5 cm. wide, acuminate, serrate or 

 serrulate, rough on both sides; heads 1 to 5, terminal and in the upper axils, 

 large; peduncles usually 5 to 18 cm. long; involucre 1.2 to 1.8 cm. high, strigose 

 and strigillose. "Hierba del pasmo" (Sinaloa). 



2. Zexmenia greggii A. Gray, PL Wright. 1: 113. 1852. 



Jalisco; type collected "between the City of Mexico and Mazatldn." 

 Suffrutescent, 2 to 3.3 meters high, similar in most characters to Z. ghies- 

 breghtii; outer and middle phyllaries triangular-ovate, acuminate. 



3. Zexmenia crocea A. Gray, PI. Wright. 1: 114. 1852. 

 Zexmenia stenaniha Hemsl. Biol. Centr. Amer. Bot. 2: 174. 1881. 

 Morelos to Michoacan and Oaxaca; type from Mexico, without definite locality. 

 Suffrutescent or truly shrubby, 0.6 to 2.5 meters high; younger branches and 



peduncles varying from densely pilose to strigose; petioles usually very short, 

 sometimes 1 cm. long; blades ovate, the larger 5 to 10.5 cm. long, acuminate, 

 usually subcordate at base, serrate, rough above, rather softly and densely 

 griseous-pubescent beneath; involucre 1.5 to 2 cm. high, subequal or obgraduate, 

 the phyfeiries few, oblong or obovate, with long loose herbaceous tips; rays orange 

 or reddish yellow. 



4. Zexmenia squarrosa Greenm. in W. W. Jones, Proc. Amer. Acad. 41: 



151. 1905. 



Guerrero and Michoacan; type from mountains above Iguala, Guerrero. 



Shrub 1 to 2 meters high; branches strigose or strigillose; petioles 1 to 1.5 

 cm. long; blades ovate, 4.5 to 7.5 cm. long, 2.5 to 6 cm. wide, acute or acuminate, 

 cuneate at base, serrate, rough above and usually beneath; heads 1 to 5, cymose, 

 on pedicels 4.5 cm. long or less; involucre 1.1 to 1.4 cm. high, the phyllaries 

 strongly graduate, broadly suborbicular-ovate or oval, hirsute-pilose, with 

 mostly obtuse squarrose herbaceous tips. 



5. Zexmenia michoacana Blake, Contr. U. S. Nat. Herb. 22: 631. 1924. 

 Michoacdn; type from Loma Santa Maria, near Morelia. 



Shrub; branchlets densely hirsute-pilose with spreading hairs; petioles 2 to 

 10 mm. long; blades ovate, 5 to 10 cm. long, 2 to 5.5. cm. wide, broadly rounded 

 to cuneate at base, rough or roughish on both sides; heads medium-sized, in 

 umbellate clusters of 1 to 6, the pedicels spreading-hirsute-pilose, 1 to 3.5 cm. 

 long; involucre 7 to 10 mm. high, the outer phyllaries mostly triangular-ovate, 

 obtuse to subacuminate, herbaceous above, mostly appressed, the inner oblong 

 or oval-oblong, rounded. 



6. Zexmenia elegans Schultz Bip.; W. W. Jones, Proc. Amer. Acad. 41: 157. 



1905. 

 Veracruz; type from Mirador. 



