Genus 60.] 



THISTLE FAMILY. 



415 



in 2-4 series. Receptacle coni; or convex, with chaffy concave scales subtending or en- 

 veloping the disk-flowers. Ray-flowers neutral, the rays entire or toothed. Disk-flowers 

 perfect, fertile, their corollas 5-lobed. Anthers entire or minutely 2-mucronate at the base. 

 Style-branches tipped with hirsute appendages. Achenes 4-angled, obtuse or truncate at 

 the apex. Pappus coroniform, sometimes of 2-4 short teeth, or none. [In honor of Claus 

 Rudbeck, 1630-1702, Swedish anatomist and botanist.] 



About 27 species, natives of North America and Mexico. In addition to the following, some iS 

 others occur in the southern and western United States. 



-X- Stem-leaves not cordate-clasping; achenes 4-angled. 

 Disk globose or ovoid and purple or dark brown in fruit; lower leaves entire or lobed. 

 Lower leaves deeply 3-lobed or 3-divided. 



Plant more or less hirsute ; leaves thin; chaff awned. 1. R. triloba. 



Plant scabrous; leaves thick; chaff blunt, pubescent at apex. 2. R. sublomenlosa. 



Leaves neither 3-lobed nor 3-divided. 



Plants hispid; chaff acute or acutish, hirsute at summit. 



Stem leaves lanceolate to oblong; involucre shorter than the rays. 3. R. hirta. 

 Stem leaves oval to obovate; involucral bracts foliaceous, nearly as long as the rays. 



4. R. Brittonii. 

 Plants pubescent or glabrate; chaff obtuse. 



Leaves denticulate or entire; rays o"-i2" long. 



Stem leaves oblong or oblong-lanceolate; disk 6" -8" broad, globose. 



5. R. fulgida. 

 Stem leaves obovate or spatulate; disk 4" -5" broad, depressed. 



6. R. spathalata. 

 Leaves dentate or laciniate; rays about 18" long. 7. R. speciosa. 



Disk elongated or cylindric in fruit, yellowish or gray; lower leaves pinuately divided or pinnatifkl. 



8. R. laciniata. 

 vr : Stem-leaves cordate-clasping; achenes nearly terete, striate. 9. R, amplexicaulis. 



i. Rudbeckia triloba L,. Thin-leaved Cone-flower. (Fig. 3883.) 

 Rudbeckia triloba L- Sp. PI. 907. 1753. 



Stem somewhat pubescent and rough, 

 rarely glabrate, branched, 2-5 high. Leaves 

 thin, rough on both sides, bright green, the 

 basal and lower ones petioled, some or all 

 of them 3-lobed or 3-parted, the lobes lanceo- 

 late or oblong, acuminate, sharply serrate; 

 upper leaves ovate, ovate-lanceolate, or lance- 

 olate, acuminate or acute, narrowed to a ses- 

 sile base or into short margined petioles, 

 serrate or entire, 2 / -4 / long, y 2 '-\' wide; 

 heads nearly 2' broad, corymbed; bracts of 

 the involucre linear, acute; pubescent, soon 

 reflexed; rays 8-12, yellow, or the base 

 orange or brownish-purple; disk dark purple, 

 ovoid, about 6" broad; chaff of the receptacle 

 awn-pointed; pappus a minute crown. 



In moist soil, New Jersey to Georgia, west to 

 Michigan, Missouri and Louisiana. Sometimes 

 escaped from gardens to roadsides. Called also 

 Brown-eyed Susan. June-Oct. 



2. Rudbeckia subtomentosa Pursh. Sweet 



Cone-flower. (Fig. 3884.) 

 Rudbeckia subtomentosa Pursh, Fl. Am. Sept. 575. 1814. 

 Densely and finely cinereous-pubescent and scab- 

 rous; stem branched above, 2-6 high. Leaves 

 thick, some or all the lower ones deeply 3-lobed or 

 3-parted, petioled, 2> / ~5 / long, the lobes oblong or 

 lanceolate, acute or acuminate, dentate; upper leaves, 

 or some of them, lanceolate or ovate, acuminate, 

 sessile or nearly so; heads numerous, 2'-i/ broad; 

 rays 15-20, yellow, or with a darker base; disc sub- 

 globose, rounded, purple, 6 // -8 // broad; bracts of the 

 involucre linear-lanceolate, acuminate, squarrose, 

 sweet-scented; chaff of the receptacle linear, obtuse 

 or obtusish, pubescent, or somewhat glandular at the 

 apex; pappus a short crenate crown. 



On prairies and along rivers, Illinois to Louisiana, Mis- 

 souri and Texas. July-Sept. 



