FLOWER IXG PLANTS AND FERNS OF ARIZONA 949 



1. Xanthium spinosum L., Sp. PL 987. 1753. 



Ash Fork to Congress Junction (Yavapai County), also in Santa 

 Cruz County, roadsides, August and September. A weed throughout 

 most of the United States and the wanner and temperate parts of 

 the world. 



2. Xanthium saccharatum Walk., Beitr. Bot. 1: 238. 1844. 

 Throughout the State, 100 to 6,000 feet, moist alluvial soil, summer. 



A common weed throughout the United States and in the Hawaiian 

 Islands, perhaps elsewhere. 



52. ZINNIA - 3 



Herbs or undershrubs; leaves opposite, entire; heads medium-sized 

 or large, radiate, showy; involucre graduated, of dry phyllaries; 

 receptacle becoming conic or cylindric; rays yellow, white, or purple, 

 pistillate, sessile and indurate-persistent on the achenes; disk achenes 

 strongly compressed; pappus none, or of 1 to 4 awns or teeth. 



The very popular garden zinnia, Z. elegans Jacq., is a native of 

 Mexico. The Arizona Z. grandiflora is an attractive plant, worthy of 

 trial for ornamental borders. 



Key to the species 



1. Annual, usually 30 cm. high or more, single-stemmed; leaves ovate or lanceo- 

 late, usually 10 mm. wide or more; rays dark red, greenish on the back. 



1. Z. MVLTIFLORA. 



1. Low perennials, normally 20 cm. high or less, much branched from the base, 



woody below; leaves linear or acerose, not more than 2.5 mm. wide; rays 



yellow or white (2). 



2. Leaves more or less 3-ribbed; rays 8 to 16 mm. long, bright yellow; style 



branches hispid, with long acuminate appendages. 2. Z. graxdiflora. 



2. Leaves 1-ribbed; rays usually 12 mm. long or less, light yellow or white; 



style branches merely hispidulous, with short bluntish appendages. 



3. Z. PUMILA. 



1. Zinnia multiflora L., Sp. PL ed. 2, 1269. 1763. 



Crassina multiflora Kuntze, Rev. Gen. PL 1: 331. 1891. 



Xear Bisbee and in the Huachuca Mountains (Cochise County . 

 base of the Patagonia Mountains and near Ruby (Santa Cruz County I , 

 4,000 to 5,300 feet, August and September. Florida and West Indies, 

 southern Arizona and Mexico; South America. 



2. Zinnia grandiflora Xutt., Amer. Phil. Soc. Trans, ser. 2, 7: 348. 



1840. 



Crassina grandiflora Kuntze, Rev. Gen. PL 1: 331. 1891. 



Xavajo County to eastern Mohave County, south to Cochise and 

 Pinal Counties, 4,000 to 6,500 feet, dry slopes and mesas, June to 

 October. Kansas to Nevada, south to Texas. Arizona, and northern 

 Mexico. 



3. Zinnia pumila A. Gray, Amer. Acad. Arts and Sci. Mem. ser. 2, 4: 



81. 1841). 



Crassina pumila Kuntze, Rev. Gen. PL 1: 331. 1891. 



Central Yavapai County to Cochise and Pima Counties, 2.500 to 

 5,000 feet, dry mesas and slopes, commonly in caliche soil, April to 

 October. Texas to southern Arizona and northern Mexico. 



73 Reference: Robinson. B. L., and Greenman, J. M. a revision of the genus zinnia. Amer. Acad. 

 Arts and Sci. Proc. 32 (Gray Herbarium Contrib. 10): 14-20. 1896. 



