CARDUACEAE 1243 
the segments entire or incised, or rarely some of them merely undulate ; petioles shorter 
than the blades : heads showy : involucres hemispheric, about 1 em. high ; bracts various, 
the outer suborbicular, the inner oblong, about twice as long as the outer, all obtuse : ray- 
flowers 12-20 ; ligules yellow, 1.5-2 cm. long: achenes cuneate to oblong-cuneate, 9-10 
mm. long, without teeth at the top. 
In open grounds, Ohio to Georgia and Alabama. Summer. 
11. Silphium brachiàtum Gattinger. Stems 1-2 m. tall, square, smooth and glau- 
cous, dichotomous above : leaf-blades scabrous above, 8-15 cm. long, the lower ones trian- 
gular-hastate, truncate or subcordate at the base, repand-toothed, acute, with petioles } as 
long as the blades, conspicuously ciliate, the upper ovate-lanceolate to lanceolate, entire or 
nearly so: involucres campanulate, about 1 cm. high ; bracts ovate to oblong, obtuse, 
ciliate, the tips often somewhat spreading: ray-flowers several; ligules yellow, 1—1.5 cm. 
long : achenes suborbicular, 6.5-7.5 mm. broad, narrowly winged and notched at the apex. 
On hillsides, Cumberland Mountains, Tennessee. Summer. 
12. Silphium trifoliatum L. Stems 1-2 m. tall, smooth, glabrousand glaucous, often 
widely branched above. Leaves in whorls of 3, or rarely opposite or alternate above ; 
blades lanceolate to linear-lanceolate, 8-10 cm. long, remotely serrate or nearly entire, 
acute or slightly acuminate, scabrous on both sides: heads often numerous, rather showy : 
involucres campanulate, about 1 cm. high ; bracts oblong-lanceolate to ovate and oblong, 
ciliate, the outer acutish, the inner obtuse: ray-flowers few ; ligules yellow, 2-2.5 cm. 
eh achenes obovate or oblong-obovate, 8-10 mm. long, narrowly winged, with 2 acute 
teeth. 
On hillsides, Pennsylvania and Ohio to Alabama. Summer. 
13. Silphium glàbrum Eggert. Stems 9-15 dm. tall, smooth, regularly leafy to the 
top, simple or:sparingly branched above. Leaves opposite or the upper ones sometimes 
alternate; blades ovate-lanceolate to lanceolate, 8-20 cm. long, acute or short-acuminate, 
remotely dentate, smooth and glabrous except along the margins: heads few: involucres 
campanulate, about 1 cm. high ; bracts oblong-lanceolate to ovate or oblong, obtuse, ciliate : 
ray-flowers several; ligules yellow, 2-2.5 cm. long: achenes obovate, 7 mm. long, with 
narrow wings and short acute teeth. 
In dry soil, North Carolina and Tennessee to Alabama and Georgia. Summer and fall. 
14. Silphium confertifolium Small. Stems 1-6 dm. tall, smooth and glabrous, 
simple or with few ascending branches above. Leaves mainly on the lower part of the 
stem, and there'approximated or crowded; blades firm, oblong to ovate-lanceolate, 6-12 
cm. long, acute or cuspidate, ciliate, nearly entire or shallowly toothed, slightly scabrous 
except near the center : involucres campanulate, 7-10 mm. high ; bracts broadly oblong, or 
oblong-obovate, obtuse, merely ciliate, with spreading or recurving tips at maturity : ray- 
flowers several; ligules yellow, 1.5-2 cm. long : achenes orbicular-cuneate, 6-7 mm. long, 
margined, with 2 ascending teeth. 
In dry soil, Alabama. Summer and fall. 
15. Silphium speciosum Nutt. Stems 6-12 dm. tall, smooth, glabrous, glaucous, 
rather corymbosely branched above, the branches sometimes pubescent. Leaves mostly op- 
posite ; blades broadly lanceolate to oblong- or ovate-lanceolate or sometimes ovate, 6-16 
cm. long, acute or slightly acuminate, usually shallowly toothed, partly clasping by a 
rounded or somewhat cordate base, scabrous above, smooth beneath : heads rather crowded 
or approximate: involucres 12-15 mm. high; bracts more or less pubescent, the outer 
broadly lanceolate to triangular, the inner broadly ovate or nearly reniform: ray-flowers 
14-26 ; ligules bright yellow, 2-2.5 cm. long: achenes oval, 11-13 mm. long, rather nar- 
rowly winged, each with a broad sinus at the top. 
On plains and prairies, Missouri and Kansas to Texas. Summer and fall. 
16. Silphium Ellióttii Small. Stems 8-13 dm. tall, scabrous or nearly smooth in age, 
corymbosely branched above. Leaves alternate, or few sometimes opposite ; blades lanceo- 
late to broadly oblong-lanceolate or rarely oval, 6-12 cm. long, entire, or occasionally with 
few indistinct teeth, conspicuously ciliate ; petioles of the lower leaves more conspicuously 
ciliate than the blades: fadi showy, often in terminal clusters: involucres 10-12 mm. 
high ; bracts oblong to suborbicular and obovate, merely ciliate, obtuse, or the outer acutish : 
ray-flowers several ; ligules 1.5-2 em. long, yellow : achenes obovate or oblong-obovate, 6-8 
mm. long, narrowly winged, each with a U-shaped sinus. 
In dry soil, North Carolina to Alabama, Summer. 
17. Silphium dentatum Ell. Stems 6-15 dm. tall, glabrous or sparingly pubescent 
near the top. Leaves opposite or the upper rarely alternate, or in whorls of 3; blades ob- 
long to lanceolate or ovate-lanceolate, 5-15 cm. long, acute, commonly coarsely dentate or 
