THISTLE FAMILY 881 



-n. -^i^i^^/l^^^*^^, ^^ sparingly short-pubescent. 31. A. Lindleyanus. 



Uasal leaf-blades lanceolate; upper stem-leaves narrowly lanceolate or those of the Inflor- 

 escence lance-lmear. ^^^^^ 



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



TT J . -. 32. A. MacCallae, 



Heads numerous ; mvolucres 5-6 mm. high; rays 8-10 mm. long; achenes hispidulous- 

 stngose. 33. a, ButlerL 



_, XV. Laeves. 



Bracts much shorter than the disk. 34 A brevibracteatus 



Bracts about equalling the disk or only slightly shorter. 

 Leaves merely scabrous-ciliate. 



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



Oreen tips of the bracts narrowly rhombic or rhomblc-oblanceolate • leaves of 



the branches gradually but not conspicuously reduced. 

 Stem-leaves lanceolate or linear-lanceolate, auricled -clasping. 



«^ , \ „ 36. A. Geyeri. 



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



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



XVI. Porter TAxr. 



One species. 39. A. Porteri. 



XVII. Salictfolii. 



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



- ^ . , ^ , .„ , 40. A. subracemosus. 



Inflorescence pamculate 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 thlckish. 



^. , „ „ 41. A. salicifoUus. 



Disk ^8 mm. high and broad; leaves tliin. 42. A. paniculatus. 



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

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



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

 Bracts linear, erect. 



Ligules purple. 44. A. fluviatilis, 



Ligules white or sometimes pinkish. 



Bracts not with wliite midrib; leaves narrowly Unear. 



45. A. Osterhoutii. 

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



^, , , , 46. A. laetivirens. 



Disk of the head 6-S mm, high and broad. 



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



47. A. longulus. 

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



48. A. roseolas. 

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



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



Inflorescence more or less flat-topped. 



Leaves lanceolate to linear-lanceolate. Arm; heads numerous. 



50. -4. corymbiformis. 

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



XVIII. LONCHOPHYLLI. 



Stem softly pubescent; leaves lanceolate, not pale. 



Stem crisi>-puberulent above; upper stem-leaves linear, sessile, but scarcely auricled. 



52. A. lonchophyllus. 

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



53. A. eriocaulis. 



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



XTX. Occident.' 



icts linear-subulate, acuminate, the imier almost caudate. 



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



55. A. subcaudatus. 

 Leaves linear. 49. A, Franklinianus. 



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



au ric ula t e-c 1 asp in g. 

 Disk about 1 cm. broad; stem-leaves linear or lance-linear; basal-leaves linear-ob- 



lanceolate; bracts distinctly imbricate in 3-4 series. 56. A, occidentalism 



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 2Hl dm. high. 



57. A. FremontiL 

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

 ^"acts with conspicuous rhombic-lanceolate green tips; dark green stem- 

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



dark blue. 



58. A. Umbachii, 



32 



