236 CARDUACEAE 



Bracts obtuse; upper leaves much reduced. 



42. C turbinatus. 

 Leaves linear to lance-linear or oblanceolate, 2-8 mm. wide. 

 Bracts linear, oblong, or lanceolate. 



Bracts at least the outer ones with thick green tips. 



31. C. linifolius. 

 Bracts comparatively thin, not green-tipped. 



Bracts linear-lanceolate, very acute. 32. C. stenolepis. 

 Bracts oblong or lanceolate, the inner obtuse. 



Involucre not viscid; leaves hispidulous ciliate-dentate. 



33. C. glaucus. 

 Inflorescence densely viscid; leaves minutely denticulate. 



34. C. riscidiflorus. 

 Bracts ovate, oval, or the inner broadly elliptic, abruptly short-cus- 

 pidate. 3.5. C. latifolius. 



Leaves and stems decidedly puberulent. 



Leaves 3-6 mm. wide, rarely twisted. 36. C. lanceulatus. 



Leaves 1-2.5 mm. wide, usually twis-ted. 



Leaves 3-nerved ; inner bracts linear, acute ; branches green or yellow- 

 ish. 37. C. puberulus. 

 Leaves 1-nerved, thick; inner bracts spatulate-oblong, rounded at 

 the apex ; branches wliite. 38. C. marianus. 

 Achenes glabrous. 



Bracts acutish; leaves flUform. 9. C. ftlifolius. 



Bracts rounded at the apex; leaves linear. 



Branches white-tomentose when young; corolla 7-10 mm. long. 



Leaves linear, more or less involute; corolla-lobes deltoid-lanceolate. 



39. C. leiospermus. 

 Leaves linear-oblanceolate, not involute; corolla-lobes linear-lanceolate. 



40. C. glarecsus. 

 Branches not tomentose; corolla 5-6 mm. long. 



Plant glabrous. 



Leaves linear-oblanceolate. 41. C. Vaseyi. 



Leaves filiform, the upper much reduced. 42. C. turbinatus. 



Plant decidedly puberulent; leaves narrowly linear. 



38. C. marianus. 



15. ISOCOMA Greene. 



Bracts acute, linear-lanceolate. 1. /. pluriflora. 



Bracts obtuse or obtusish, line.nr, oblong, or oblanceolate. 

 Leaves 1-ribbed, the lower often toothed. 



Plant herbaceous, except the suffruticose base; bracts comparatively tliin. 



2. /. Wrightii. , 

 Plant slirubby; brads much thickened, especially at the apex. 3. /. acradenia. 

 Leaves triple-nerved, entire. -i. /• scopulorum. 



16. PRIONOPSIS Nutt. 1. P. ciliata. 



17. SIDERANTHUS Nutt. Iron Plant. 

 Leaves spinescent-toothed, not pinnatiP.d. 



Heads discoid; perennials, with woody caudex. 



Heads ped uncled. 1. S. grindelinides. 



Heads sessile. 2. S. abcrrans. 



Heads radiate; annuals. 



Leaves oblanceolate, spinulose-tipped; plant more or less viscid. 3. S. annuus. 

 Leaves linear-oblanceolate, bristle- tipped; plant strigose. 4. S. gracilis. 



Leaves pinnatifld; perennials, -svith a short woody base; achenes somewhat flattened. 

 Stem more or less floccose or cinereous, especially when young. 



Plant cinereous pubescent, more or less glandular. 5. S. australis. 



Plant more or less floccose, not at all glandular. 6. S. spinulosus. 



Plant neither floccose nor cinereous. 



Plant perfectly glabrous or sparingly glandular-puberulent. 7. S. glaberrimus. 

 Plant flneh puberulent, or hispid. 



Heads hemispheric; bracts slightly glandular. 8. S. puberulus. 



Heads somewhat turbinate; bracts densely glandular-puberulent. 



9. S. turbinellus. 



18. PYRROCOMA Nutt. 



Heads apparentlv discoid, the sterile rays being concealed in the pappus. 



Inner bracts recurved cuspidate. 1. P- subsquarrosa. 



Bracts not recurved cuspidate. 



Bracts oblong or oval; heads hemispheric. 



Leaves and bracts more or less spinulose-toothed, the latter with a narrow 

 scarioas margin. 2. P. carthamoides. 



Leaves and bracts not spinulose-toothed, the latter with a broad scarious erose 

 margin. 

 Pappus sordid; plant almost glabrous. 3. P. rigida. 



Pappus brownish red; plant villous. 4. P. erythropappa. 



Bracts lanceolate; head campanulate-turbinate. ii. P. Cusickii. 



Heads distinctly radiate. 



Bracts except the innermost obtuse, obovate or oblong. 6. P. crocea. 



