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-cleft 

 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. 



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 o.val 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. ^?. itmbrosa. 



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. 



1. R. triloba. 



2. R. subtomentosa. 



3. R. hir'a. 



