1018 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



9496) may belong to a different species, but the material available 

 is insufficient for identification. C. alsophila is the southwestern 

 representative of the widespread tropical and subtropical American 

 C. nutans (L.) Polak., differing from that species primarily in the much 

 shorter, stouter, densely hispidulous beak of its achene. 



122. PEREZIA 15 



Perennial herbs, with alternate, sessile and often clasping, spinulose- 

 toothed leaves and lavender-pink heads, the stem woolly-tufted at 

 base ; involucre strongly graduate; flowers all hermaphrodite, bilabiate, 

 the outer lip 3-toothed, the inner lip 2-parted; achenes subcylindric or 

 fusiform, densely glandular or glandular-hispidulous; pappus of 

 numerous scabrous bristles. 



Key to the species 



1. Heads solitary, broad, about 15- to 24-flowered; leaves suborbicular or obovate- 

 suborbicular, 2 to 5 cm. long and about as wide, coarsely and unequally 

 spinulose-dentate; plant usually dwarf, sometimes up to 25 cm. high. 



1. P. NANA. 



1. Heads numerous, panicled, narrow, 4- to 11-flowered; leaves mostly ovate, 

 larger, normally much longer than wide, usually more evenly spinulose- 

 denticulate; plants taller, 40 to 150 cm. high (2). 

 2. Phyllaries obtuse or merely acutish, not glandular; heads 8- to 11-flowered. 



2. P. WRIGHTII. 



2. Phyllaries strongly acuminate, stipitate-glandular; heads 4- to 6-nowered. 



3. P. THURBERI. 



1. Perezia nana A. Gray, Amer. Acad. Arts and Sci. Mem. ser. 2, 4: 



111. 1849. 



Maricopa, Pinal, Cochise, and Pima Counties, up to 5,000 feet, 

 mesas and slopes, usually under bushes, March to June. Texas to 

 Arizona and northern Mexico. 



Desert-holly, an attractive little plant, making a good ground cover 

 where sufficiently abundant. The flowers are delightfully fragrant, 

 with an odor of violets. The roots of this species and of P. wrightii 

 yield pipitzahoic acid, which may be used in chemical analysis as an 

 indicator of alkalinity. 



2. Perezia wrightii A. Gray, PL Wright. 1: 127. 1852. 



Perezia arizonica A. Gray, Bot. Calif. 1: 422. 1876. 



Throughout most of the State, not above 6,000 feet, foothills and 

 canyons, common, January to June (sometimes autumn), type of P. 

 arizonica collected in Arizona, without definite locality (Palmer). 

 Western Texas to southern Utah, Arizona, and northern Mexico. 



The pink flowers are honey-scented. The root was used as a styptic 

 by the Indians. 



3. Perezia thurberi A. Gray, Amer. Acad. Arts and Sci. Mem. ser. 



2, 5: 324. 1854. 

 Mountains of Cochise, Santa Cruz, and Pima Counties, 4,000 to 

 6,000 feet, slopes and canyons, June to October. Southwestern New 

 Mexico and southern Arizona to central Mexico. 



15 Reference: Bacigaltjpi, Rimo. a monograph of the genus perezia, section acoxjrtia, with a 

 provisional key to the section EUPEREziA. Gray Herbarium Contrib. 97: 1-81. 1951. 



