FLOWERING PLANTS AND FERNS OF ARIZONA 963 



streams, January to October, type from Camp Lowell, Pima County 

 (Lemmon in 1880). Southern Arizona and northern Mexico. 



73. HETEROSPERMA 



Low slender annual; leaves opposite, once or twice pinnately divided 

 into linear lobes; heads small, terminal, radiate, yellow; involucre 

 double, much as in Coreopsis ; rays fertile ; outer aehenes oval, incurved, 

 wing-margined, epappose; inner aehenes narrower, often infertile, not 

 margined, narrowed into a beak, their pappus of 2 deciduous awns. 



1. Heterosperma pinnatum Cav., Icon. PI. 3: 34. 1795. 



Near Flagstaff (Coconino County), near Prescott (Yavapai County), 

 south to Cochise, Santa Cruz, and Pima Counties, commoner in south- 

 ern Arizona, 5,000 to 6,000 feet, rich soil, sometimes on limestone, 

 August and September. Southwestern Texas to Arizona, south to 

 Guatemala. 



74. THELESPERMA 



Slender perennials; leaves opposite, mostly pinnately parted into a 

 few narrow lobes ; heads medium-sized or small, long-peduncled, radiate 

 or discoid, entirely yellow or the disk brownish: involucre double, the 

 outer phyllaries narrow, herbaceous, the inner ones broad, scarious- 

 margined. connate to about the middle or higher ; pales of the receptacle 

 broadly scarious-margined ; aehenes oblong to linear, thickish, more or 

 less papillate; pappus of 2 retrorsely hispid awns, or obsolete. 



Key to the species 



1. Lobes of the disk corollas lanceolate or linear, longer than the throat; pappus of 

 2 triangular hispid teeth 1 mm. long or longer; plants usually 30 to 60 cm. 

 high, leafy below, naked above, usually branched; heads normally discoid, 

 rather large, the disk 1 to 1.5 cm. thick; outer phyllaries very short, broadly 



ovate, rounded 1. T. megapotamicum. 



1. Lobes of the disk corollas ovate, shorter than the throat; pappus a mere crown 



or obsolete; plants normally 40 cm. high or less, very leafy below, with long 



naked erect peduncles (2). 



2. Heads relatively large (the disk about 1 to 1.5 cm. thick), normally with 



conspicuous rays; leaf divisions lanceolate to linear, 1.5 to 6 mm.' wide; 



involucre about 9 mm. high; inner phyllaries with broad and conspicuous 



scarious margins 2. T. subxudum. 



2. Heads small (the disk 5 to 10 mm. thick), always discoid; leaf divisions fili- 

 form, about 0.5 mm. wide; involucre 4 to 5 mm. high; inner phyllaries 

 less conspicuously scarious-margined 3. T. loxgipes. 



1. Thelesperma megapotamicum (Spreng.) Kuntze, Rev. Gen. PI. 3 2 : 

 182. 1898 (as Thelespermum) . 



Bidens megapotamica Spreng., Svst. Veg. 3: 454. 1826. 

 Bidens gracilis Torr.. Ann. Lyc.'X. Y. 2: 215. 1828. 

 Thelesperma gracile A. Grav, Jour. Bot. and Kew Gard. Misc. 

 1: 252. 1849. 



Apache, Navajo, Yavapai, Pinal, Cochise, Santa Cruz, and Pima 

 Counties, 4,000 to 7,000 feet, grassy plains and mesas, May to Septem- 

 ber. Nebraska and Wyoming to Utah, south to Texas, Arizona, and 

 Mexico ; southern South America. 



The Hopi make a tea from the flowers and young leaves, which are 

 dried and then boiled. A reddish-brown dye for baskets and textiles 

 is also obtained bv them from this plant. 



