. STANDLEY TEEES AND SHRUBS OF MEXICO 1487 



Leaves strongly glandular-punctate; young growth glabrous. 

 Leaves linear-filiform, subterete. 



Involucre about 6-seriate, 6 to 7 mm. high; rays present. 



4. A. palmeri. 

 Involucre about 4-seriate, 5 mm. high or less; rays wanting. 



6. A. propinquus. 

 Leaves linear or linear-spatulate, distinctly flattened; phyllaries all 

 linear-lanceolate to oblong, acute to acuminate. 

 Phyllaries linear-lanceolate or linear-subulate, acuminate; leaves 1 to 



L5 mm. wide 7. A. laricifolius. 



Phyllaries oblong or oblong-lanceolate, acute; leaves 0.6 to 0.9 mm. 



wide 8. A. parrasanus. 



Heads distinctly cymose-panicled, rarely racemose-panicled. 



Stem densely tomentose-. 12. A. pyramidatua. 



Stem not tomentose. 



Leaves linear-filiform, terete or subterete, conspicuously impressed- 

 punctate (less so in no. 4). 

 Involucre 6 to 7 mm. high, about 6-seriate, the inner phyllaries 



narrowly linear; rays present 4. A. palmeri. 



Involucre 3 to 6 mm. high, about 4-seriate, the inner phyllaries 



oblong or linear-oblong; rays wanting (rarely solitary in no. 5). 



Involucre 3 to 4 mm. high, the phyllaries with short greenish 



tips; heads subsessile, in close cymose clusters, these panicu- 



lately or subracemosely arranged 5. A. sonoriensis- 



Involucre 4 to 6 mm. high, the phyllaries without distinct greenish 

 tips; heads pedicellate. 

 Bracts in distinct vertical ranks; heads 5 to 7-flowered. 



(Chrysothamnus paniculatus.) 

 Bracts not in distinct vertical ranks; heads 8 to 12-flowered. 



6. A. propinquus. 

 Leaves linear or linear-spatulate, flat, inconspicuously or not punctate 

 (except in nos. 10 and 4). 

 Leaves 5 to 15 mm. long; heads usually with 1 or 2 rays. 



10. A. monactis. 

 Leaves 2 cm. long or more; heads discoid. 



At least the middle phyllaries with definite greenish tips. 



Middle phyllaries obtuse or rounded; involucre 4 to 5 mm. high. 



14. A. drummondii. 

 Middle phyllaries acute; involucre 5 to 7 mm. high. 



20. A. fasciculatus. 

 Phyllaries without definite greenish tips, but sometimes obscurely 

 greenish toward tip. 

 Leaves obscurely or not punctate, 2 mm. wide or more. 



15. A. heterophyllus. 



Leaves strongly punctate, 1.2 mm. wide or less,. 4. A. palmeri 



Leaves more than 3 mm. wide (if rarely less, not entire), usually toothed or 



pinnatifid. 



Leaves opposite throughout; phyllaries about 2-seriate, subequal, the outer 



broadly oval-oblong, about 2.5 mm. wide 2. A. oppositifolius. 



Leaves alternate; phyllaries several-seriate, graduate, much narrower. 

 Leaves entire. 



Plant tomentose 21. A. canus. 



57020—26 12 



