CARDUACEAE 
Involucres eylindric-turbinate or cylindric- 
campanulate, about 2 mm. thick, 
Braets of the involucre obtuse: stems 
and leaves somewhat shaggy-pubes- 
cent: leaf-bladesappressed-serrate. 
Bracts of the involucre acute: stemsand 
leaves scabrous-pubescent: leaf- 
blades sharply serrate. 
Involucrescampanulate,about 3mm. thick. 
Leaf-blades rugose-veiny. 
Leaf-blades decidedly acute or acuminate, mostly 
over thrice as long as broad. 
Leaf-blades obtuse or acutish, mostly about twice 
as long as broad. 
T T Stem glabrous, at least below the inflorescence. 
Branches of the inflorescence pubescent. 
Involuere cylindric, few-flowered. 
Involuere not spirally twisted. 
Inner bractsof the involucre3 mm.long,obtuse. 
Inner bracts of the involucre 4mm. long, acute. 
Involuere spirally twisted. 
Involuere campanulate, many-flowered. 
Leaf-blades relatively thick, singly serrate except 
in robust plants of S. strigosa. 
Branches of the inflorescence short and ap- 
proximate, forming a compact pyramidal 
panicle. 
Branches of the inflorescence elongated and 
remote, when abbreviated, the head-clus- 
ters in an elongated interrupted thyrsus. 
Involucre 3-4 mm. high. 
Leaf-blades glabrous, smooth. 
Leaf-blades strigose. scabrous. 
Involucre 5-6 mm. high. 
Cauline leaves, or some of them, with 
finely and closely toothed blades: 
leaves of the inflorescence-branches 
linear to linear-lanceolate. 
Cauline leaves, or some of them, with 
coarsely or remotely toothed blades: 
leaves of the inflorescence-branches 
elliptic to cuneate. 
Leaf-blades relatively thin, mainly doubly ser- 
rate with spreading teeth. 
Involucres 3.5-4.5 mm. high, 2-2.5 mm. thick. 
Involucres 5-6 mm. high, 3-4 mm. thick. 
Branches of the inflorescence glabrous. 
Involucre less than 5 mm. high. 
Bracts of the involucre obtuse : involucre cam- 
panulate. 
Inner bracts of the involucre 0.5 mm. wide: 
basal leaves with serrate blades. 
Inner bracts of the involucre 1 mm. wide: 
basal leaves with crenate blades. 
Bracts of the involucre acute: involucre cylindric. 
Involucre over 5 mm. high. 
Lower leaves with romotely toothed blades: 
achenes 2.5-3 mm. long. 
Lower leaves with closely toothed blades: achenes 
1.5-2 mm. long. 
* * Leaf-blades manifestly 3-ribbed. 
Stem glabrous. 
Cauline leaves abruptly smaller from near the base of the stem : 
leaves erect or appressed : achenes glabrous. 
Cauline leaves not abruptly smaller above the base of the stem : 
achenes pubescent. 
Branches of the inflorescence glabrous. 
Involucres campanulate : species trans-Alleghenian. 
Involucres cylindric-campanulate: species Carolinian. 
Branches of the inflorescence pubescent. 
Stem pubescent, rarely minutely so, or only in lines. 
Cauline leaves with relatively long blades, acuminate or at- 
tenuate. : 
Involucres 5-6 mm. high. 
Involucres 2-4 mm. high. 3 
Cauline leaves with blades of a linear type. 
Involucre about 4 mm. high. 
Involucre turbinate-campanulate : leaf-blades long- 
attenuate. 
Involucre broadly campanulate: leaf-blades acu- 
minate. 
Involucres 2-3 mm. high. 
Cauline leaves with blades of a lanceolate or oblong-lan- 
ceolate type. 
Cauline leaves with relatively short blades, obtuse or merely 
46. 
48. 
52. 
1191 
. S. Earlei. 
. S. pendula. 
51. 
S. strigosa. 
. S. rugosa. 
. S. celtidifolta. 
S. ulmifolia. 
. S. microphylla. 
S. Helleri. 
. S. Elliottii. 
S. Boottii. 
. S. strigosa. 
S. Yadkinensis. 
53. S. Ludoviciana. 
57. 
58. 
mÓ 
. S. arguta. 
S. Vaseyi. 
. S. juncea. 
'S. gracillima. 
S. delicatula. 
. S. austrina. 
. S. neglecta. 
61. S. Gattingeri. 
. S. Missouriensis. 
. S. pinetorum. 
S. serotina. 
. S. Shortii. 
. S. Nashii. 
. S. Leavenworthit. 
. S. rupestris. 
. S. Canadensis. 
acute. i 
Blades of the upper leaves narrow, or if relatively broad closely sessile. 
