1302 



CARDUACEAE 



141. SYNOSMA Raf. 



Perennial caulescent glabrous or nearly glabrous herbs. Leaves alternate : blades 

 toothed, often triangular or hastate. Heads homogamous, discoid, corymbose. Involucres 

 nearly cylindric : bracts narrow, 12-15 in 1 series, with few subulate ones at their bases. 

 Receptacle flat, naked. Corollas tubular, white or pink. Anthers not tailed at the base. 

 Stigmas obtuse or truncate, unappendaged. Achenes narrow, 5-10-ribbed. Pappus copi- 

 ous, of soft hair-like bristles. The plants flower in summer and fall. INDIAN PLANTAIN. 



1. Synosma suavfeolens (L. ) Britton. Stems 6-15 dm. tall. Leaves numerous; 

 blades narrowly or broadly hastate, 8-20 cm. long, acute or acuminate, sharply and often 

 doubly serrate or dentate-serrate, the lower ones cordate at the base, slender-petioled, the 

 upper ones truncate or cuneate at the base, sessile or nearly so : involucral bracts glabrous, 

 the larger ones about 12, linear or slightly broadened upward, 7-11 mm. long, acute or 

 acuminate : achenes slender, 7-8 mm. long. 



In low grounds or shaded soil, Connecticut to Minnesota, Florida and Tennessee. 



142. SENECIO L. 



Annual or perennial caulescent herbs. Leaves alternate, sometimes mainly basal : 

 blades various, entire, toothed, pinnatifid or pinnately parted. Heads solitary, or numer- 

 ous and variously disposed, radiate or rarely discoid. Involucres campanulate to cylin- 

 dric : bracts narrow, mainly in one series, the few outer irregular. Receptacle flat or 

 slightly convex, usually naked or pitted. Ray-flowers pistillate, fruit-producing. Disk- 

 flowers fruit-producing : corollas tubular, yellow. Anthers obtuse at the base or rarely 

 slightly sagittate. Stigmas, at least in the disk-flowers, spreading or recurving. Achenes 

 terete, or those in the disk slightly flattened, 5-10-ribbed. Pappus copious, of slender or 

 capillary smooth or rough bristles. SQUAW-WEED. RAGWORT. RAG-WEED. GROUNDSEL. 



Involucre over 12 mm. high. 1. S. Rugdia. 



Involucre less than 12 mm. high. 

 Annual or merely biennial plants. 



Leaf-blades lyrately and pinnately divided : involucre less than 6 mm. high. 

 Stem simple at the base, or if branched, the terminal leaf-segment is 



lobed not toothed. 



Terminal leaf-segments reniform, few-lobed. 

 Terminal leaf-segments not reniform, several-many-toothed. 

 Stem branched at the base. 



Leaf-blades entire or repand-toothed : involucre over 6 mm. high. 

 Perennial sometimes shrubby plants. 



A. Plants herbaceous : leaves mainly crowded on a caudex, from which 



arises the much less leafy flowering stem. 

 Blades of the basal leaves cordate or truncate at the base. 



Blades of the basal leaves predominatingly lanceolate or oblong-lan- 



2. S. Mi*sis$ippianus. 



3. S. lobatus. 



4. S. Greggii. 



5. S. ampuUaceut.'. 



ceolate, sharply serrate. 

 Blades of the basal leaves predominatingly orbicular or ovate, crenate. 

 Involucres over 5 mm. high. 

 Involucres less than 5 mm. high. 



Blades of the basal leaves gradually narrowed or cuneate at the base. 

 Blades of the basal leaves scarcely longer than broad. 

 Blades of the basal leaves manifestly or markedly longer than broad. 

 Basal leaves with merely toothed or. partially and slightly lyrate- 



pinnatifld blades. 



Blades of the basal leaves wholly, or predominatingly, nar- 

 rowly or broadly spatulate : achenes glabrous. 

 Leaf-blades toothed or pinnatifid, like the stem, essentially 



glabrous. 

 Leaf-blades entire, like the stem, persistently grayish- white 



tomentose. 

 Blades of the basal leaves wholly or predominatingly oblong, 



oval or lanceolate : achenes pubescent. 

 Bracts of the mature involucre less than 6 mm. long. 

 Blades of the basal leaves mainly 1 cin. wide. 

 Blades of the basal leaves mainly 2 cm. wide. 

 Bracts of the mature involucre over 6 mm. long. 

 Receptacle 3 mm. broad at maturity. 

 Receptacle 4-5 mm. broad at maturity. 



Main stem and leaf-blades persistently more or less 



pubescent. 

 Bracts of the involucre becoming glabrous : blades 



of the basal leaves serrate. 

 Bracts of the involucre persistently pubescent: 



blades of the basal leaves crenate. 

 Main stem and leaf-blades glabrous. 



Blades of the basal leaves pinnately parted and twice or thrice 

 pinnatifid or dissected. 



6. S. Robbinsii. 



7. S. aureus. 



8. -S. gractti*. 



9. S. rotundus. 



10. S. obovatus. 



11. S. Purshianus. 



12. S. Balmmitae. 



13. S. Earlei. 



14. S. Smattii. 



15. S. Plattensis. 



16. S. tomentosus. 



17. S. Alabamensis. 



