190 
Atlantic States. A Texan form is var. MICROPRYLLA Gray, which is reduced and 
rather rigid, with lower leaves 5 cm. long, and upper reduced to 1 cm., obtuse, ob- 
scurely serrate, 
12. S. Boottii Hook. Smooth or scabrous-pubescent or below hirsute, slender, 
often branched, 6 to 15 dm. high: leaves rather finely serrate, ovate to oblong- 
lanceolate, pointed; the upper small, oblong to narrowly lanceolate, often entire: 
heads loosely racemose: rays 1 to 5 or none.—Dry ground, extending into Texas from 
the Southern States. 
++++ Leaves more or less plainly 3-ribbed (lateral ribs almost obsolete in no. 18): heads in 
one-sided spreading or recurved racemes, forming an ample panicle, 
= Smooth and glabrous, at least the stem and bright green leaves. 
13. S. Missouriensis Nutt. Smooth throughout, 3 to 9 dm. high: leaves firm and 
rather rigid, linear-lanceolate, or the lower broadly lanceolate, tapering to both 
ends, with very rough margins, the teeth (ifany) sharp and rigid: heads and dense 
crowded racemes forming a crowded and flat corymb-like panicle: involucral bracts 
thickish.—Dry prairies throughout the State. 
14. S. serotina Ait. Stem stout, 6 to 21 dm. high, smooth, often glaucous: leaves 
thinner, quite smooth both sides, lanceolate, taper-pointed, very sharply serrate (ex- 
cept the narrowed base), rough-ciliate: the ample panicle pubescent: involucral 
bracts thin, chiefly linear.—Moist or rich soil throughout the State, passing into 
var. GIGANTEA Gray, which is commonly tall, 15 to 24 dm. high, with leaves more or 
less pubescent or hispidulous beneath. 
== Pubescent (at least the stem) or hispidulous-scabrous. 
15. S. Canadensis L. Stem rough-hairy, tall and stout, 9 to 18 dm. high: leaves 
lanceolate, pointed, sharply serrate (sometimes almost entire), more or less pubescent 
beneath and rough above: heads small: rays very short.—-Common throughout the 
State. Exceedingly variable in the roughness and hairness of the stem and leaves, 
the latter oblong-lanceolate or elongated linear-lanceolate. Var. procera Torr, & 
Gray has leaves whitish-woolly beneath; var. scaABRA Torr. & Gray has leaves very 
rough above, often entire, rugose-veined; var, CANESCENS Gray, of southwestern 
Texas, has the stem and both surfaces of the narrow and commonly entire leaves 
canescent with soft and fine pubescence. 
16. S. nemoralis Ait. Clothed with a minute and close grayish-hoary (soft or 
roughish) pubescence: stem simple or corymbed at summit, 1.5 to 7.5 dm. high: 
leaves oblanceolate or spatulate-oblong, the lower somewhat crenate-toothed and 
tapering into a petiole: racemes numerous, dense, at length recurved, forming a 
large and crowded compound raceme or panicle which is usually turned to one side: 
involucral bracts linear-oblong, appressed: rays 5 to 9.—Dry hills or sterile soil, 
throughout Texas. 
17. S. radula Nutt. Stem and oblong or obovate-spatulate leaves rigid and very 
rough, not hoary, the upper sessile: involucral bracts oblong, rigid: rays 3 to 6: 
otherwise nearly as in the last.—Dry hills and prairies, extending into Texas from 
the western Mississippi States. 
18. S. sparsiflora Gray. Scabro-puberulent, somewhat cinereous, leafy into the 
narrow and strict branches of the panicle: leaves all small (the larger hardly 2.5 
em. long), lanceolate-linear, rather acute at both ends, rigid, entire, with lateral 
ribs and veins almost obsolete: heads somewhat scattered or few in the short imper- 
fectly racemiform and somewhat secund clusters,6 mm, long: rays to 6 to 10, 
little surpassing the disk.—Llano Estacado, northwestern Texas. 
+++-+ Heads in a compound terminal corymb, not at all racemose: leaves mostly with a 
strong midrib. 
++ Leaves not 3-nerved. 
19. S. rigida L. Rough and somewhat hoary with a minute pubescence: stem 
stout, 6 to 15 dm. high, very leafy: corymb dense: leaves oval or oblong, copiously 
