THISTLE FAMILY 881 



Plant glabrous or sparingly short-pubescent. 31. A. Lindleijanus. 



Basal le<af-blades lanceolate ; upper stem-leaves narrowly lanceolate or those of the iiiilor- 

 escencc lance-linear. 

 Heads few; involucres 8-9 mm. high; rays about 15 mm. long; achenes glabrous. 



32. A. MacCallae. 

 Heads niunerous; involucres 5-6 mm. high; rays 8-10 mm. long; achenes hispidulous- 

 strigose. 33. A. Butleri. 



XV. Laeves. 

 Bracts much shorter than the disk. 34. A. brevibracteatus. 



Bracts about equalUng the disk or only slightly shorter. 

 Leaves merely scabrous-ciliate. 



Green tips of the bracts broadly rhombic; leaves of the branches much reduced. 



35. A. laevis. 



Green tips of the bracts narrowly rhombic or rhombic-oblanceolate ; leaves of 

 the branches gradually but not conspicuously reduced. 

 8tem-leaves lanceolate or linear-lanceolate, auricled-clasping. 



36. A. Gct/eri. 

 Stem-leaves narrowly linear, not auricled. 37. A. subsalignus. 



Leaves decidedly long-cUiate; bracts with oblong green tips. 38. A. Scribneri. 



XVI. PORTERIANI. 



One species. 39. A. Porleri. 



XVII. SALICIFOLir. 



Inflorescence falsely racemose; leaves linear to oblanceolate ; leaves triple-nerved. 



40. A. subracemosus. 

 Inflorescence paniculate or corymbiform; leaves not triple-nerved. 



Inflorescence elongate, not flat-topped. 



Heads numerous in a much branched panicle; involucre well imbricate. 

 Leaves distinctly toothed. 



Disk of the head about 1 cm. high and broad; leaves thickish. 



41. A. salicifolius. 

 Disk 6-S mm. liigh and broad; leaves thin. 42. A. paniculatus. 



Leaves entire, rarely denticulate, with more or less clasping bases. 

 Disk of the head nearly 1 cm. high and broad. 



Bracts hnear-filiform, more or less squarrose. 43. A. hesperius. 

 Bracts linear, erect. 



Ligules purple. 44. A. fluviatilis. 



Ligules white or sometimes pinkish. 



Bracts not with white midrib; leaves narrowly linear. 



45. A. Osterhoutii. 

 Bracts with white midrib; leaves lanceolate or oblong-lanceolate. 



46. A. laetivirens. 

 Disk of the head 6-8 mm. high and broad. 



Bracts Unear, nearly of the same length; leaves narrowly Unear. 



47. A. longuhis. 

 Bracts oblong or linear-oblong, the outer shorter; leaves broadly Unear. 



48. A. roseolas. 

 Heads rather few, often soUtary on the leafy branches; bracts narrowly Unear, 



nearly of the same length, the outer green. 49. A. Franklinianus. 



Inflorescence more or less flat-topped. 



Leaves lanceolate to linear-lanceolate, firm; heads numerous. 



50. A. corymbiformis. 

 Leaves narrowly linear, thin; heads few. 51. A. junciformis. 



XVIII. LONCHOPHYLLI. 



Stem softly pubescent; leaves lanceolate, not pale. 



Stem crisp-puberulent above; upper stem-leaves Unear, sessile, but scarcely auricled. 



52. A. lonchophyllus. 

 Stem viUous above; upper stem-leaves oblong-lanceolate, auriculate-clasping. 



53. A. eriocaulis. 

 Stem hispidiilous above; leaves linear, pale green. 54. A. leucopsis. 



XIX. OCCIDENT.\LE3. 



Bracts Unear-subulate, acuminate, the inner almost caudate. 



Leaves Unear-oblanceolate, acuminate, or the upper linear-lanceolate. 



55. A. subcaudatus. 

 Leaves linear. 49. A. Franklinianus. 



Bracts linear, acute; lower leaves oblanceolate, the upper lanceolate, acute, usually 

 auriculate-clasping. 

 Disk about 1 cm. liroad; stem-lea vas Unear or lance-Unear; basal-leaves Unear-ob- 

 lanceolate; bracts dLstinctly imbricate in 3-4 series. 56. A. occidentalis. 

 Disk 1.5 cm. or more wide; leaves lanceolate or oblanceolate, entire; bracts in about 

 2 series. 

 Bracts, at least the outer ones, wholly green; plant 2-4 dm. high. 



57. A. Fremontii. 

 Bracts with more or less distinct white margins below, green-tipped above. 

 Bracts with conspicuous rhombic-lanceolate green tips; dark green stem- 

 leaves oblanceolate, all except the uppermost crenato and petioled; rays 

 dark blue. 58. A. Umbachii. 



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