FLOWERING PLANTS AND FERNS OF ARIZONA 883 



48. Rays 10 or more, much longer than wide; achenes obpyramidal, 



5-angled, hirsute 98. Actixea. 



47. Rays not persistent on the achenes (49). 



49. Achenes strongly flattened, 2-edged; pappus of 1 or 2 bristlelike 



awns and sometimes with a crown of squamellae (50). 

 50. Pappus of 1 or 2 awns and with a crown of squamellae; achenes 

 usually callous-margined and ciliate 83. Perityle. 



50. Pappus of 1 or 2 awns, without squamellae; achenes not callous- 



margined, not ciliate 84. Laphamia. 



49. Achenes not flattened or 2-edged; pappus awns or squamellae 

 more numerous (51). 



51. Pappus squamellae dissected into numerous bristles, these 



united at base (52) . 

 52. Heads short-peduncled, solitary; rays conspicuous. 



88. Syntrichopappus. 



52. Heads essentially sessile, clustered; rays inconspicuous. 



93. Eriophyllum. 

 51. Pappus squamellae not dissected into bristles (53). 



53. Phyllaries spreading or reflexed, herbaceous (54). 



54. Receptacle naked; pappus usually much shorter than the 

 achene 99. Helenium. 



54. Receptacle fimbrillate; pappus usually as long as the achene 



or longer 100. Gaillardia. 



53. Phyllaries erect (55) . 



55. Plant a low annual, not woolly; leaves opposite, linear, 



entire; pappus of 2 to 5 lanceolate awns.. 86. Baeria. 



55. Plants perennial, or woolly, or with more numerous awns 



or paleae in the pappus (56). 



56. Achene obpyramidal, strongly 4-angled; ray 1; pappus of 



8 scarious paleae or squamellae; slender annuals, with 



leaves entire or pinnately divided into filiform lobes. 



89. Schkuhria. 



56. Achene not obpyramidal and 4-angled; rays more than 



1 (57). 



57. Rays (2 t>o 5) fertile, disk flowers (6 to 7) sterile; leaves 



dissected into filiform lobes; heads very small, very 



numerous, crowded in dense cymose panicles. 



101. Plummera. 



57. Both rays and disk flowers fertile, more numerous (58). 



58. Pappus of 12 or more lanceolate awn-tipped paleae; 



plant nearly glabrous, with dissected leaves; 



involucre not double 91. Hymenothrix. 



58. Pappus paleae fewer, or else the plant tomentose, 



or the leaves not dissected, or the involucre 



double, of 2 more or less distinct sets of phyllaries 



(59). 



59. Achenes obpyramidal, 5-angled, only 2 or 3 times 



as long as wide 98. Actinea. 



59. Achenes narrowly obpyramidal, several times as 



long as wide (60). 



60. Phyllaries concave, partly enclosing the ray 



achenes; plants woolly, 93. Eriophyllum. 



60. Phyllaries flat, not at all enclosing the ray 



achenes; plants not woolly 96. Bahia. 



1. STEVIA 56 



Herbs or shrubby plants; leaves alternate or opposite; heads small, 

 5-flowered; phyllaries 5 or 6, equal, firm; corollas tubular, 5-toothed, 

 white to purple; achenes slender; pappus of awns or squamellae or 

 both, or reduced to a toothed crown. 



56 Reference: Robinson, B. L. the stevias of north America. Gray Herbarium Contrib. 90: 90-159. 

 1930. 



