1244 CARDUACEAE 
dentate-serrate : heads corymbose: involucres about 1 cm. high ; bracts ovate-lanceolate to 
suborbicular, oblong or oblong-cuneate, merely ciliate, the outer ones acute, the inner ob- 
tuse : ray-flowers several ; ligules yellow, 2-3 em. long: achenes obovate to oval, 6-8 mm. 
long, winged, the teeth rounded, or the sinus nearly obsolete. 
In sandy soil, South Carolina to Florida and Alabama. 
18. Silphium Simpsónii Greene. Stems 9-12 dm. tall, less densely pubescent above 
than below, often sparingly branched above. Leaves whorled or opposite, or alternate above ; 
blades various, those of the basal leaves oblong to lanceolate-oblong, 10-15 cm. long, on 
short-margined petioles, those of the upper part of the stem ovate or broadly ovate, 3-10 
em. long, sessile and half-clasping by broad bases, all coarsely crenate-serrate or slightly 
repand : heads few : involucres 2-2.5 cm. broad ; bracts suborbicular to ovate, merely cilio- 
late: ray-flowers 12-16 ; ligules yellow, 2.5-3 em. long: achenes obovate or orbicular-ob- 
ovate, 10-13 mm. long. 
In sandy pine lands, southern peninsular Florida. Summer. 
19. Silphium Asteríscus L. Stems 6-15 dm. tall, corymbose above, scabrous-pu- 
bescent. Leaves oppositeor sometimes alternate on the upper part of the stem ; blades 
oblong to oblong-lanceolate or ovate-lanceolate, more or less distinetly serrate, those of 
the lower leaves petioled : heads showy : involucres campanulate, about 1 em. high : bracts 
oblong-lanceolate to oval and oblong, obtuse, or the outer ones acutish, merely ciliate : ray- 
flowers 11-15; ligules 1.5-2 cm. long: achenes oval or obovate-oval, 7-9 mm. long, sur- 
mounted by acute teeth. 
In dry soil, Virginia to Ohio, Florida and Mississippi. Summer and fall. 
20. Silphium angüstum (A. Gray) Small. Stems 6-12 dm. tall, simple or sparingly 
branched above, scabrous-pubescent. Leaves mostly alternate, few on the upper part of 
the stem ; blades narrowly oblong or narrowly oblong-lanceolate, 2-10 cm. long, repand- 
serrate or nearly entire, the upper ones sessile or partly clasping: heads solitary orfew, 
showy: involucres campanulate, barely 1 cm. high; bracts ovate to orbicular or broadly 
spatulate, ciliate, the outer acute, the inner obtuse: ray-flowers several ; ligules yellow, 
2-2.5 em. long: achenes broader than high, 9-19 mm. broad, surmounted by short teeth. 
In sandy soil, western Florida. Summer. 
21. Silphinm Gatésii Mohr. Stems 6-15 dm. tall, hispid, simple or sparingly 
branched above. Leaves alternate ; blades broadly linear to oblong-lanceolate or lanceo- 
late, 5-14 cm. long, acute, remotely serrate, scabrous-pubescent, the lower ones short- 
petioled : heads showy : involucres campanulate, barely 1 cm. high ; bracts lanceolate to 
ovate and oblong, hispid, the outer acute and short-acuminate, the inner obtuse: ray- 
flowers several; ligules yellow, 12-20 mm. long! achenes suborbicular or broader than 
high, the teeth forming a broad sinus. 
In dry soil, Missouri to Tennessee and Alabama. Spring and summer. 
22. Silphium scabérrimum Ell. Stems 9-15 dm. tall, glabrous, or sparingly pubes- 
cent above. Leaves opposite or the upper ones sometimes alternate: blades oblong-lance- 
olate, ovate-lanceolate or narrowly ovate, 10-20 cm. long, or rather shorter high up on the 
stem, acute or somewhat acuminate, sharply serrate, scabrous on both sides ; petioles about 
3 as long as the blades near the base of the stem, gradually shorter above: heads usually 
few, showy : involucres campanulate, about 1 cm. high ; bracts oblong-lanceolate to ovate or 
oblong, not conspicuously pubescent, but ciliate, obtuse or the outer ones acutish, the inner 
with recurved tips: ray-flowers several ; ligules about 1.5 cm. long, yellow : achenes sub- 
orbicular, 5-7 mm. broad, broadly winged, with a deep notch at the apex. 
In open woods and fields, Virginia and Tennessee to Georgia and Mississippi. Summer. 
23. Silphium integrifólium Michx. Stems 8-15 dm. tall, rough-pubescent, 4-angled 
or striate-ridged. Leaves opposite or mainly so ; blades ovate to broadly lanceolate, quite 
uniform in size, 7-12 cm. long, scabrous on both sides, acute, often shallowly toothed on 
the lower part of the stem, mostly entire above : heads in rather open corymbs : involucres 
1-1.5 em. high ; bracts more or less pubescent, the outer triangular-ovate to lanceolate, 
acute, the inner broader, obtuse: ray-flowers 15-23 ; ligules bright yellow, 9-3 cm. long: 
achenes narrowly obovate, about 1 cm. long, broadly winged only near the top, the broa 
teeth forming a V-shaped sinus. . 
On plains and prairies, Wisconsin to Illinois, Mississippi and Texas. Summer and fall. 
24. Silphium aspérrimum Hook. Stems 7-14 dm. tall, closely scabrous-pubescent, 
branching above. Leaves pubescent like the stem, the lower opposite, the upper alternate ; 
blades ovate to lanceolate, 5-10 cm. long, acute, entire or undulate, sessile and often partly 
clasping : heads showy, on densely white-bristly peduncles: involucres 1-1.5 em. high; 
