1600 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



90. PERITYLE Benth. Bot. Voy. Sulph. 23. pi. 15. 1844. i 

 Reference: Rydberg, X. Amer. Fl. 34: 12-19. 1914. 



Herbs or undershrubs; leaves usually opposite at least below, petioled, entire 

 to dissected; heads radiate or discoid, white or yellow; involucre sub-2-seriate, 

 equal, the phyllaries carinate at least at maturity; rays fertile; disk corollas 

 i-toothed; achenes linear or oblong, strongly compressed, usually with distinct, 

 white, callous, ciliate margins; pappus a crown of more or less connate squamel- 

 lae, and usually 1 or 2 slender bristlelike awns, or rarely wanting. 



Several of the species included in this treatment ma\' be merely herbaceous. 

 Heads discoid. 



Plant white-tonientose; heads numerous, naked-panicled 1. P. incana. 



Plant green; heads solitary or few 6. P. jaliscana. 



Heads radiate. 



Leaves deeply cut or lobed. 



Pappus awn 1, much shorter than the achene 7. P. lineariloba. 



Pappus awns 1 or 2, as long as the achene. 



Pappus awns 2; involucre cinereous-puberulent 8. P. coronopifolia. 



Pappus awn 1; involucre hirsute or villous. 



Leaf blades usually 5-lobed, very thin, nearly glabrous. 15. P. lobata. 



Leaf blades 3-lobed, thickish, glandular-pubescent 16. P. trisecta. 



Leaves not deeply cut or lobed. 



Rays white, 2 to 4 mm. long; pappus awns 2 (rarely 1 or none). 



Achenes glabrous on the faces; leaf blades nearly or quite entire, 1 to 



3 cm. long 3. P. rosei. 



Achenes pubescent on the faces; leaf blades usualh' coarsely toothed, if 

 entire only 3 to 8 mm. long. 

 Leaf blades 3 to 8 mm. long, entire or 1 or 2-toothed on each side. 

 Petioles usually much longer than the blades; disk corollas merely 



glandular on the teeth 4. P. hof meisteria. 



Petioles shorter than the blades; disk corollas hirsute-pilose on the 



teeth 5. P. trichodonta. 



Leaf blades 1 to 5 cm. long, coarsely dentate 2. P. spilanthoides. 



Rays yellow, rarely white (?), 5 to 10 mm. long; pappus awn 1 or none. 

 Stems puberulent or glandular-puberulent. 



Stem puberulent, obscurely if at all glandular; pappus awn as long as 



the achene or longer 9. P. leptoglossa. 



Stem glandular-puberulent; pappus awn about one-third as long as the 



achene 10. P. parryi. 



Stems viscid-villous. 



Achenes strongly ciliate; pappus awn about twice as long as the achene. 



11. P. cordifolia. 

 Achenes obscurely ciliate; pappus awn not twice as long as the achene, 

 or wanting. 

 Leaves shallowly lobed, the lobes acutely toothed; squamellae well 



developed 12. P. palmeri. 



Leaves dentate or doubly dentate, not lobed; squamellae minute or 

 wanting. 



Leaf blades 1 to 2.5 cm. long; pappus present 13. P. lloydii. 



Leaf blades 4 to 7 cm. long; pappus wanting. _ 14. P. grandifolia. 



1 The related genus Amauria Benth. is described by Rydberg as consisting of 

 suffruticose perennials, but the two known species are winter annuals. 



