GENUS 60. 



THISTLE FAMILY. 



469 



60. SPILANTHES Jacq. Stirp. Am. 214. pi. 126. 1763. 



Annual or perennial branching herbs, with opposite, usually toothed leaves and rather 

 small, long-peduncled discoid and radiate heads, terminal, or in the upper axils, or rays 

 wanting in some species. Involucre campanulate, its bracts in about 2 series, herbaceous, 

 loosely appressed. Receptacle convex or elongated, chaffy, its chaff embracing the disk- 

 achenes and at length falling away with them. Ray-flowers yellow, or white, pistillate, some- 

 times wanting. Disk-flowers yellow, perfect, their corollas tubular with an expanded 4-5-cle ft 

 limb. Anthers truncate at the base. Style-branches of the disk-flowers long, sometimes 

 penicillate at the summit. Ray-achenes 3-sided, or compressed, those of the disk-flowers 

 compressed, margined. Pappus of 1-3 awns, or more. [Greek, spot- or stain-flower, not 

 significant.] 



About 30 species, natives of warm and tropical regions. Type species : Spilanthes urens Jacq. 



i. Spilanthes repens (Walt.) Michx. 

 Spilanthes. Fig. 4441. 



Anthemis repens Walt. Fl. Car. 211. 1788. 

 Spilanthes repens Michx. Fl. Bor. Am. 2: 131. 1803. 

 S. americana repens A. H. Moore, Proc. Am. Acad. 

 42: 547. 1907. 



Perennial, usually rooting at the lower nodes ; 

 stem slender, simple or branched, spreading or 

 ascending, 8'-2 long, pubescent, or nearly gla- 

 brous. Leaves ovate to lanceolate, petioled, acute 

 or acuminate at the apex, or the lower obtuse, 

 coarsely toothed, or nearly entire, i'-3' long; 

 heads long-peduncled, solitary at the end of the 

 stem and branches, 6"-io" broad ; bracts of the 

 involucre oblong to oblong-lanceolate, obtuse or 

 acute ; rays 8-12, yellow ; receptacle narrowly 

 conic ; achenes oblong, most of them roughened 

 when mature and hispidulous ; pappus of I or 2 

 very short awns, or none. 



In moist or wet soil, Missouri to Texas, east to 

 South Carolina and Florida. June-Sept. 



61. RUDBECKIA L. Sp. PI. 906. 1753. 



Perennial or biennial (rarely annual), mostly rigid, usually rough or hispid herbs, with 

 alternate undivided lobed or pinnatifid leaves, and large long-peduncled heads of tubular 

 (mostly purple) and radiate (yellow) flowers. Involucre hemispheric, its bracts imbricated 

 in 2-4 series. Receptacle conic or convex, with chaffy concave scales subtending or envelop- 

 ing 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 30 species, natives of North America and Mexico. In addition to the following, some 20 

 others occur in the southern and western United States. Type species : Rudbeckia hirta L. 



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

 Lower leaves deeply 3-lobed or 3-divided. 



1. R. triloba. 



2. R. subtomentosa. 



3. R. hirta. 



Plant more or less hirsute ; leaves thin ; chaff awned. 

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

 Leaves neither 3-lobed nor 3-divided. 



Plants hispid ; style-branches subulate. 



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

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



4. R. Brittonii. 



Plants pubescent or glabrate ; style-branches obtuse. 

 Chaff merely ciliate. 



Leaves denticulate or entire; rays 9"- 12" long. 



Basal leaves narrowed at base. 5. R. fulgida. 



Basal leaves cordate at base. 6. R. umbrosa. 



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



Chaff canescent. 8. R. grandiflora. 



Disk elongated or cylindric in fruit, yellowish or gray. 



Leaves very thick, shallowly toothed. 9 . R. maxima. 



Leaves thin, pinnately divided or pinnatifid. 10. R.laciniata. 



